Composite framework metal loaded multi-scale molecular sieve nanocatalyst, and preparation method and application thereof

Abstract

This invention discloses a composite framework metal-supported multi-scale molecular sieve nanocatalyst, its preparation method, and its application, belonging to the technical field of composite materials. The invention involves mixing tetrapropylammonium hydroxide with anhydrous ethanol, adding a metal salt, and then adding a silicon source under stirring. The mixture is then crystallized to obtain a seed solution. A sodium aluminate solution is added to the seed solution, and glass fibers are impregnated in the solution. The mixture is centrifuged and dried to obtain seed-supported metal-framework glass fibers. These fibers are then subjected to steam-assisted crystallization. The product is dried, calcined, and ground to obtain the composite framework metal-supported multi-scale molecular sieve nanocatalyst. The preparation method of this invention is highly operable, and the prepared material can simultaneously leverage the advantages of nano-metals and multi-scale porous molecular sieves, exhibiting advantages such as large specific surface area, high crystallinity, and structural stability. In practical water purification applications, it can solve the disadvantages of nano-metal particles such as easy oxidation, agglomeration, and difficulty in recovery, while also improving mass and heat transfer efficiency and catalytic efficiency, thus exhibiting superior catalytic properties.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and particularly relates to a composite framework metal-supported multi-scale molecular sieve nanocatalyst, its preparation method and application. Background Technology

[0002] Freshwater resources, as one of the necessities for sustaining human life and various organisms, have a crucial impact on human survival and development. How to purify and remediate industrial polluted water bodies in a green and efficient manner, and improve the economic benefits of industrial polluted water treatment, is a pressing practical problem facing humanity (Energy environment.mater, 2021, 4(04): 611-619). Currently, scientists have proposed a series of technical means for the separation, purification, and in-situ remediation of industrial wastewater, including flocculation sedimentation, biodegradation, selective adsorption, and membrane filtration (Chin.J.Chem.Eng, 2023, 59: 222-230). However, these traditional methods generally suffer from low treatment efficiency and poor reusability, thus failing to thoroughly and effectively treat industrial wastewater. For example, adsorption methods are costly and inefficient (J Hazard Mater, 2008, 158: 499-506); biodegradation technology is economical and green, but it is difficult to treat organic pollutants with large differences in biochemical properties and complex structures, resulting in low degradation efficiency and preventing large-scale industrial application (Appl. Catal. B Environ, 2010, 98(1): 10-26). Therefore, finding an economical, efficient, green, and non-toxic water purification technology is urgently needed.

[0003] Advanced oxidation processes (AOPs) are considered one of the most effective emerging technologies for aquatic environment remediation, attracting widespread attention due to their strong oxidizing power, high reaction rate, and broad applicability to the degradation of organic compounds (Chem.Eng.J, 2013, 218:260-266). However, further industrial water purification applications have revealed that not all AOP methods are suitable for real-world wastewater degradation. Some AOP methods suffer from high power consumption, high oxidant content, and the need for high reaction temperatures and system pressures to meet real-world water purification requirements (Catalysts, 2018, 8(12):673-673). Among the various AOPs currently used for real-world polluted water purification, CWO shows significant application potential. By using highly efficient and stable catalysts to alter the reaction process, it reduces the temperature and pressure required for the oxidation reaction, greatly improving the actual water purification effect and oxidation efficiency (Roy.Soc.Open.Sci, 2018, 5(3):171731). CWO water purification processes can be divided into homogeneous and heterogeneous processes. Among them, the typical homogeneous method—the Fenton process—is a common industrial wastewater treatment technology, but it still has drawbacks such as limited pH application range and difficulty in catalyst recovery (Appl. Catal. A Gen, 2009, 357(2):135-141). Heterogeneous processes can effectively overcome the above drawbacks, that is, the application of heterogeneous catalysts with active catalytic components introduced on the carrier material in polluted water bodies. It exhibits the advantages of easy catalyst separation and recovery, less loss of active components, and green and economical water purification process (Polymers, 2022, 14(13):2749-2749). The selection of carrier materials and the method of introducing active components are also the focus of current research.

[0004] Among numerous carrier materials, molecular sieves have attracted widespread attention due to their unique microstructure and physicochemical properties. Molecular sieves are a class of aluminosilicate crystals with regular channels, consisting of a framework structure composed of silicon and aluminum connected by oxygen bridges. This framework structure contains many channels with uniform pore size and some neatly arranged vacancies with large internal surface areas. This unique microporous structure makes them play an important role in adsorption, catalysis, separation and other fields (Micropor.Mesopor.Mat, 2022, 331). Among them, ZSM-5 molecular sieve is a type of molecular sieve with a high silicon-to-aluminum ratio. It has good acid and alkali resistance, good shape selectivity, high specific surface area and a wide range of silicon-to-aluminum ratios for synthesis, making its crystal structure easy to control. It has been widely used in the chemical industry (J.Environ.Chem.Eng, 2020, 8(5)). Almghar synthesized a novel PANI@Fe-ZSM-5 hybrid composite material through in-situ interfacial polymerization and applied it to the adsorption treatment of OG dye wastewater. This hybrid composite material not only exhibited the good redox reversibility and excellent structural stability of PANI, but also showed the excellent adsorption capacity and good reusability of iron-loaded molecular sieves (Chemosphere, 2022(5):295). Peng synthesized a Pd / Fe-ZSM-5 bimetallic composite catalyst for toluene catalytic emission reduction. Compared with single metal-based catalysts, it showed higher catalytic activity, better service life and water resistance in toluene combustion (Catal.Today, 2019, 332).

[0005] However, ZSM-5 molecular sieve fiber materials currently used in industry generally suffer from problems such as limited intracrystalline diffusion, pore blockage, and severe coking due to their small micropore channel diameter, making it difficult to achieve their maximum performance in industrial applications (Che m. Soc. Rev, 2017, 46(2): 481-558). In recent years, it has been proven feasible to synthesize molecular sieves with hierarchical structures and different levels of porosity for industrial catalytic processes (Ind. Eng. Chem. Res, 2016, 55(17): 4948-4959). As a member of multi-level molecular sieves, multi-scale molecular sieves have a large cavity volume and an interconnected structure of macropore-mesopore-micropore multi-level channels, which are easy to modify and functionalize. They can effectively reduce the diffusion resistance within the reaction, improve the mass transfer rate, enhance the efficient heterogeneous catalytic reaction process, and improve the catalytic efficiency and reaction performance in practical applications. In addition, the multi-level channel structure of multi-scale molecular sieve fibers effectively slows down the carbon deposition rate in the pores and extends the service life of the catalyst. The self-supporting structure of multi-scale molecular sieves can also avoid the problems caused by the presence of a support, such as affecting diffusion and mass transfer, obscuring active sites, reducing specific surface area and packing density (Chem.Sci,2016,7(2):1582-1587). In current research, there are many methods for preparing multi-scale and multi-level molecular sieve fibers. Dai prepared hollow ZSM-5 single crystals with silicon-rich surfaces through a dissolution-recrystallization strategy. However, this method inevitably involves the post-processing of silicon waste and toxic etchants in a time-consuming etching process, which may lead to product deactivation, loss of active sites, particle aggregation and structural damage (Adv. Funct. Mater, 2015, 25(48):7479-7487). Ding synthesized a novel B-ZSM-5 / SS fiber catalyst with a hollow structure in situ through a seed-assisted dry gel vapor phase method, which avoids the adverse effects of poor heat transfer and high pressure drop on traditional zeolite particles in a fixed-bed reactor. It significantly improved the reaction efficiency and catalytic activity in the methanol-to-propylene reaction. However, due to the unsatisfactory additional shedding process in the alkaline leaching process, its service life was also shortened, which is not conducive to the large-scale development of this composite material (Chem. Eng. J, 2018, 361:588-598).

[0006] Currently, most heterogeneous supported molecular sieve fiber catalysts are synthesized by ion exchange or impregnation methods. Since the binding force between transition metal ions / oxides and the zeolite framework is relatively weak, the existing impregnation and ion exchange methods will cause the introduced active metal heteroatoms to accumulate on the outer surface of the zeolite. In practical applications, metal ion leaching and agglomeration will occur, leading to a series of application problems such as secondary pollution, short service life, and poor cycle performance. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a composite framework metal-supported multi-scale molecular sieve nanocatalyst, its preparation method, and its applications. This invention uses glass fiber as a substrate and forms a multi-scale molecular sieve through gel technology and steam-assisted synthesis. It leverages the high catalytic performance of metal particles while utilizing the excellent thermal stability, hydrothermal stability, and good shape selectivity of molecular sieves to enhance catalyst activity. The hydrothermal synthesis method allows the active metal component to enter the molecular sieve framework structure, avoiding the problems of easy enrichment and leaching of the introduced active metal caused by traditional impregnation methods. This solves a series of application problems such as difficult catalyst recovery, short service life, and poor cycle performance. Simultaneously, macroscopic adjustment and optimization of the framework metal content can effectively control the catalyst surface acidity and also inhibit the growth of supported metal grains and maintain high metal dispersion. Compared with traditional supported metals, the framework metal of this invention exhibits higher stability, utilization rate, and reaction efficiency during catalysis, and shows higher CO2 selectivity for the catalytic degradation of organic pollutants. Furthermore, loading metals onto multi-scale molecular sieves solves the problems of difficult recovery and low regeneration efficiency of traditional catalysts, and also increases the contact efficiency between the catalyst and pollutants in water. Simultaneously, it is easy to separate during practical use, improving recovery efficiency and avoiding secondary pollution. In summary, the composite nanofiber material of this invention possesses excellent catalytic performance and practical application capabilities.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] One of the technical solutions of the present invention:

[0010] This invention provides a method for preparing a composite framework metal-supported multi-scale molecular sieve nanocatalyst, comprising the following steps: mixing tetrapropylammonium hydroxide (TPAOH) with anhydrous ethanol, adding a metal salt simultaneously, then adding a silicon source under stirring, crystallizing, and preparing a seed solution; then adding sodium aluminate (NaAlO2) solution to the seed solution, then immersing glass fibers in the seed solution containing NaAlO2 solution, centrifuging, and drying to obtain a metal framework glass fiber loaded with seed crystals; subjecting the seed-loaded metal framework glass fiber to steam-assisted crystallization; drying the product, calcining to remove the organic template agent, and grinding to obtain the composite framework metal-supported multi-scale molecular sieve nanocatalyst.

[0011] This invention employs an in-situ solid-to-solid conversion method, using glass fiber as the carrier material. During the growth of molecular sieve crystals on the carrier material, the carrier material is gradually transformed and removed, while metal ions are embedded into the molecular sieve framework. This ultimately yields a multi-scale, multi-level molecular sieve with a well-crystalled, self-supporting hierarchical structure, avoiding the need to remove toxic etching agents and clean the silicon source. This effectively improves the mechanical strength and catalytic performance of the molecular sieve crystals. Furthermore, the strong interaction between the metal compound and the molecular sieve carrier ensures the metal is firmly fixed to the carrier, solving the problems of easy agglomeration and leaching in traditional molecular sieves. Simultaneously, choosing glass fiber as the carrier material shifts the control of the multi-scale molecular sieve structure from microscopic to macroscopic operations, improving the controllability and operability of the multi-scale molecular sieve structure.

[0012] The metal salt includes one of soluble iron salt, soluble copper salt, soluble cobalt salt, and soluble molybdenum salt.

[0013] For example, the metal salt is one of FeSO4·7H2O, CuSO4·5H2O, CoSO4·7H2O, FeCl2·6H2O, CuCl2·2H2O, CoCl2·6H2O, and MoCl3·6H2O.

[0014] The molar ratio of TPAOH, anhydrous ethanol and silicon source is 10:(10-50):(10-50).

[0015] The silicon source is silicon tetrachloride, dichlorosilane, silane, or tetraethyl orthosilicate (TEOS).

[0016] The crystallization temperature is 60–140°C, and the time is 30–60 h.

[0017] The mass ratio of glass fiber to seed solution is (0.1-1):12, that is, the mass of glass fiber added to every 12g of seed solution is 0.1-1g.

[0018] The concentration of the NaAlO2 solution is 0.3–0.8 mol / L, preferably the concentration of the sodium aluminate solution is 0.4 mol / L.

[0019] The immersion time is 10–20 hours; and / or

[0020] The centrifugation is performed at 5-8 r / s for 40-80 s.

[0021] The steam-assisted crystallization is carried out at a temperature of 110–200°C for a time of 15–35 hours; and / or

[0022] The calcination temperature is 450–700℃, and the time is 3–8 hours, preferably 4 hours; and / or

[0023] The molar ratio of the metal salt to the silicon source is (1:60) to (1:180).

[0024] The second technical solution of the present invention:

[0025] The present invention also provides a composite framework metal-supported multi-scale molecular sieve nanocatalyst prepared according to the above method.

[0026] The composite framework metal-supported multi-scale molecular sieve nanocatalyst prepared by this invention has good crystallinity and excellent catalytic performance. The metal catalyst and the support have strong interaction. In practice, it has good catalytic effect in purifying organic dye wastewater, high mechanical strength, and strong reusability, giving full play to the excellent performance of each component.

[0027] The third technical solution of the present invention:

[0028] The present invention also provides the application of the aforementioned composite framework metal-supported multi-scale molecular sieve nanocatalyst in the removal of pollutants from water bodies.

[0029] For example, the pollutant is an organic compound, preferably an organic compound having an aromatic ring.

[0030] This invention employs an in-situ solid-phase recrystallization transformation synthetic route to prepare molecular sieve nanocatalysts with multi-scale structures. This avoids the need for substrate material treatment after crystallization in traditional methods, effectively improving the mechanical strength and catalytic performance of the molecular sieve crystals. The synthesis process significantly reduces heat treatment time. Furthermore, the addition of metal salts during the seed crystal preparation process greatly improves the mixing and uniformity of the components, facilitating the formation of better composite framework metal crystals. Simultaneously, this invention embeds the active metal component into the molecular sieve framework structure, avoiding the metal ion leaching and agglomeration phenomena that occur on the outer surface of the molecular sieve due to traditional loading methods, thus greatly improving the catalyst's lifespan and cycle performance. The composite framework metal-supported multi-scale molecular sieve nanocatalysts of this invention exhibit high mechanical strength, strong regeneration capacity, controllable metal framework, controllable metal loading amount and loading position, a simple and easy preparation method, and ideal macroscopic structure and catalytic performance. Metal compounds and molecular sieves have strong interaction forces. When applied to actual wastewater treatment systems, they can simultaneously leverage the advantages of both metal compounds and molecular sieve supports, improving mass and heat transfer efficiency and contact efficiency, thereby enhancing catalytic efficiency. Furthermore, they can firmly bind the catalyst to the support, reducing the leaching and loss of metal ions, extending the catalyst's lifespan, and lowering regeneration and recycling costs.

[0031] This invention employs a hydrothermal synthesis method to incorporate metallic active components into the molecular sieve framework structure, synthesizing multi-scale molecular sieve fibers containing a metal framework. In practical applications, this avoids the aforementioned drawbacks. Macroscopic adjustment and optimization of the framework metal content can effectively control the acidity of the catalyst surface, and also inhibit the growth of supported metal grains and maintain high metal dispersion. Simultaneously, the framework metal exhibits higher stability, utilization rate, and reaction efficiency during catalysis compared to the non-framework metal, demonstrating higher CO2 selectivity for the catalytic degradation of organic pollutants.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] (1) Simplified synthesis steps and strong operability. The composite framework metal-supported multi-scale molecular sieve nanofiber material of the present invention adopts a direct solvent-free in-situ solid-solid conversion method. Metal salts are introduced during the preparation of seed crystals. Glass fibers are transformed into multi-scale molecular sieves with porous structures through the hydrolysis and condensation of Si-O-Si bonds. The metal elements exist in the molecular sieve framework in the form of ions or atoms, which simplifies the process of introducing metal elements and avoids the need for additional processing of organic waste and removal of carrier materials required by traditional preparation methods. This method is simple, efficient, green and economical. At the same time, the acidity of the catalyst surface can be controlled by macroscopically adjusting the content of the introduced metal components according to actual needs. It has the effect of effectively inhibiting the growth of supported metal grains and maintaining high metal dispersion, and is easy to put into actual production and application.

[0034] (2) Superior Physicochemical Properties. This invention utilizes a simple hydrothermal synthesis method to introduce the active metal component onto a multi-scale molecular sieve framework support. This solves the problem of the introduced active metal heteroatoms easily accumulating and detaching from the outer surface of the zeolite due to traditional methods, avoiding rapid catalyst deactivation and secondary pollution, and greatly improving the product's service life and cycle performance. Simultaneously, this invention selects glass fiber as the support material, and the synthesized molecular sieve framework contains cations with balanced charges (such as Na). + This characteristic gives the catalyst surface more active sites, which can better bind with reactants in the reaction. In addition, the framework metal exists in a different form than traditional extra-framework metals. It forms chemical bonds with other atoms in the molecular sieve framework (such as Si, O, etc.), and has a stronger interaction force with the molecular sieve crystal. It also increases the surface charge and acidity of the catalyst, and exhibits higher stability, utilization and reaction efficiency in the catalytic process. It has higher CO2 selectivity for the catalytic degradation of organic pollutants (that is, the degradation effect is more complete, more methylene blue is converted into CO2 rather than intermediate products, and the total organic carbon (TOC) of the reaction system is significantly reduced).

[0035] (3) Higher practical application value. The composite framework metal-supported multi-scale molecular sieve nanofiber material of this invention exhibits excellent catalytic performance, strong regeneration ability, low deactivation constant, abundant pore size, and strong interaction between the metal component and the molecular sieve support. It can simultaneously leverage the advantages of both the active metal component and the molecular sieve support, not only improving mass and heat transfer efficiency and contact efficiency, but also reducing the shedding and leaching of metal components, avoiding the problem of easy agglomeration of traditional metal catalysts, and enhancing its application capability in actual production. The composite framework metal-supported multi-scale molecular sieve nanofiber material has superior performance, is easy to synthesize, and is flexible in use, possessing good industrial application value. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 The microstructure of the composite framework metal-supported multi-scale molecular sieve nanocatalyst prepared in Example 1 is shown.

[0038] Figure 2 The crystal morphology and elemental distribution of the composite framework metal-supported multi-scale molecular sieve nanocatalyst prepared in Example 1 are shown. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0045] All raw materials used in the embodiments of this invention were purchased commercially. For example, quartz fiber and glass fiber were purchased from Shanghai Xinhu Experimental Equipment Co., Ltd.

[0046] In some embodiments of the present invention, a method for preparing a composite framework metal-supported multi-scale molecular sieve nanocatalyst is provided, comprising the following steps: mixing tetrapropylammonium hydroxide (TPAOH) with anhydrous ethanol, adding a metal salt, and then adding a silicon source under stirring, crystallizing to prepare a seed solution; then adding sodium aluminate (NaAlO2) solution to the seed solution, immersing glass fibers in the seed solution containing NaAlO2 solution, centrifuging, and drying to obtain a metal framework glass fiber loaded with seed crystals; subjecting the metal framework glass fiber loaded with seed crystals to steam-assisted crystallization, drying the product, calcining to remove the organic template agent, and grinding to obtain a composite framework metal-supported multi-scale molecular sieve nanocatalyst.

[0047] Due to the presence of metal elements in the molecular sieve framework, the molecular sieve framework prepared in this invention contains cations with balanced charges (such as Na). +This characteristic gives the resulting material more acidic and active sites, and an increased number of structural defects, allowing it to better bind with reactants in the reaction and exhibiting unique and superior performance in catalysis and adsorption. In existing molecular sieve materials prepared by impregnation, Fe is supported on the surface of the molecular sieve, which readily forms oxides with air, reducing the surface charge of the catalyst and decreasing its acidity. However, in this invention, iron is added during the seed crystal preparation process. After the molecular sieve is formed, the iron exists in ionic or atomic form within the molecular sieve framework, forming chemical bonds with other atoms in the framework (such as Si, O, etc.), thus increasing the overall charge of the catalyst material and promoting catalytic reactions. In existing catalysts prepared by impregnation or ion exchange, the active component Fe is entirely located on the surface of the molecular sieve, resulting in weak interaction with the support. This leads to easy detachment during the reaction, causing rapid catalyst deactivation and the risk of secondary pollution. In this invention, Fe exists within the molecular sieve framework, remaining stable during the reaction and exhibiting strong stability. This invention uses glass fiber as raw material, which contains not only SiO2, but also elements such as aluminum oxide, calcium oxide, boron oxide, magnesium oxide, and sodium oxide, giving the final molecular sieve cationic properties and improving the performance of the molecular sieve nanocatalyst.

[0048] In this invention, since hydrogen peroxide solution (H2O2) is a strong oxidant and is also unstable, it is easy to decompose into water and oxygen. It will slowly decompose over time, causing it to deteriorate. Therefore, it needs to be prepared and used immediately to ensure accurate concentration and purity of solute.

[0049] It should be noted that all aspects not described in detail in this invention are conventional operating methods in the field and are not the focus of this invention. For example, specific methods such as the preparation method of hydrogen peroxide solution are all completed using conventional methods.

[0050] This invention employs an in-situ solid-phase recrystallization transformation route to prepare molecular sieve nanocatalysts with multi-scale structures. This avoids the need for substrate material treatment after crystallization in traditional methods, effectively improving the mechanical strength and catalytic performance of the molecular sieve crystals. The synthesis process significantly reduces heat treatment time. Furthermore, the addition of metal salts during the seed crystal preparation process greatly improves the mixing and uniformity of the components, facilitating the formation of crystals with better composite framework metals. Simultaneously, this invention embeds the active metal component into the molecular sieve framework structure, avoiding the metal ion leaching and agglomeration phenomena that occur on the outer surface of the molecular sieve due to traditional loading methods, thus significantly improving the catalyst's lifespan and cycle performance. The composite framework metal-supported multi-scale molecular sieve nanocatalysts of this invention exhibit high mechanical strength, strong regeneration capacity, controllable metal framework, controllable metal loading amount and loading position, a simple and easy preparation method, and ideal macroscopic structure and catalytic performance. The strong interaction between metal compounds and molecular sieves allows for the simultaneous utilization of the advantages of both the metal compound and the molecular sieve support in practical wastewater treatment systems. This improves mass and heat transfer efficiency and contact efficiency, thereby enhancing catalytic efficiency. Furthermore, it ensures the catalyst is firmly bonded to the support, reducing metal ion leaching and loss, extending catalyst lifespan, and lowering regeneration and recycling costs. The composite framework metal-supported multi-scale molecular sieve nanocatalyst of this invention can efficiently remove pollutants from water, especially organic compounds with aromatic rings. The preparation method of this invention is highly operable, and the prepared material simultaneously leverages the advantages of nano-metals and multi-scale porous molecular sieves, exhibiting advantages such as large specific surface area, high crystallinity, and structural stability. In practical water purification applications, it addresses the drawbacks of nano-metal particles, such as easy oxidation, agglomeration, and difficulty in recovery, while also improving mass and heat transfer efficiency and catalytic efficiency, resulting in superior catalytic properties. Methylene blue is used as an example in some typical embodiments of this invention.

[0051] In an embodiment of the present invention, the methylene blue degradation rate is calculated as follows: the absorbance of the solution is measured using a UV-Vis spectrophotometer, and the methylene blue degradation rate (%) is calculated according to the formula: methylene blue degradation rate (%) = (initial absorbance - absorbance) / initial absorbance × 100%; the metal ion leaching concentration is calculated as follows: metal ion leaching concentration (mg / L) = dilution factor × data value measured by inductively coupled plasma atomic emission spectrometry.

[0052] The technical solution of the present invention will be further illustrated by the following embodiments.

[0053] Example 1

[0054] A method for preparing composite framework iron-supported multi-scale molecular sieve nanocatalysts:

[0055] (1) Preparation of seed solution from seed gel

[0056] (1-1) Take out a dry and clean beaker, pour in 8.8g (0.0108mol) TPAOH (25wt.% aqueous solution) and 2g (0.0435mol) ETOH (anhydrous ethanol) that have been weighed in advance, and then add 0.1103g (0.0004mol) FeSO4·7H2O as an iron source to prepare skeletal iron. Place the beaker on a magnetic stirrer and add 9.92g (0.0476mol) TEOS dropwise while stirring.

[0057] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 25TPAOH / 110SiO2 / 853.45H2O / 100ETOH / 0.92Fe that can be used directly.

[0058] The calculation process for preparing the seed solution is as follows:

[0059] M(TPAOH) = 203.36 g / mol, m(TPAOH(25% aqueous solution)) = 8.8 g, n(TPAOH) = (8.8 * 25%) / 203.36 = 0.010818 mol, n(H2O) = (8.8 * 75%) / 18 = 0.366667 mol;

[0060] M(TEOS) = 208.33 g / mol, m(TEOS) = 9.92 g (containing 1 molecule of Si), n(SiO2) = 9.92 g / mol

[0061] 208.33 = 0.047617 mol;

[0062] M(EtOH)=46.07g / mol, m(EtOH)=2g, n(EtOH)=2 / 46.07=0.043412mol;

[0063] M(FeSO4·7H2O)=278.01g / mol, m(FeSO4·7H2O)=0.1103g, n(Fe)=0.1103 /

[0064] 278.01=0.000397mol, n(H2O)=(7*0.1103) / 278.01=0.002777mol;

[0065] a TPAOH=b SiO2=x H2O=y EtOH=z Fe. Let b=110, then a=(110*0.010818) /

[0066] 0.047617≈25; x=(110*(0.366667+0.002777)) / 0.047617≈853.45; y=(110*0.043412) / 0.047617≈100; z=(110*0.000397) / 0.047617≈0.92. Therefore, the result is 25TPAOH / 110SiO2 / 853.45H2O / 100ETOH / 0.92Fe.

[0067] (2) Preparation of seed-supported glass fibers by impregnation method

[0068] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0325g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0069] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0070] (3) Preparation of composite framework iron-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0071] (3-1) Tear the glass fiber loaded with seed crystals into pieces with tweezers and place it in a raised polytetrafluoroethylene support. The support is located in the middle of the polytetrafluoroethylene liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner and then put the liner into an oven for steam-assisted crystallization at 150℃ for 24h.

[0072] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0073] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, thus obtaining a composite framework iron-supported multi-scale molecular sieve nanocatalyst.

[0074] The microstructure of the composite framework metal-supported multi-scale molecular sieve nanocatalyst prepared in Example 1 is shown in [Figure 1]. Figure 1 Crystal morphology and elemental distribution are shown in Figure 2 .from Figure 2As can be seen, Si, Al, and O elements are uniformly distributed on the surface of the molecular sieve fibers, proving that the prepared sample has good crystallinity. Fe element is also uniformly distributed within the molecular sieve, indicating that the metal ions of the catalyst of this invention are successfully embedded in the molecular sieve framework. Figure 1 As can be seen, the molecular sieve nanocatalyst exhibits good crystallinity. The layered molecular sieve crystals stack together to form a self-supporting hierarchical structure, with a molecular sieve layer thickness exceeding 3 μm. This stabilizes the fiber structure and provides more active sites. The microporous structure inherent in the molecular sieve crystals, the mesoporous structure formed by crystal stacking, and the intermediate macroporous structure together constitute the multi-level structure of the composite framework metal-supported multi-scale molecular sieve nanocatalyst, endowing it with excellent catalytic performance.

[0075] Composite framework iron-supported multi-scale molecular sieve nanocatalysts have important applications in wastewater treatment, as they can firmly support and reduce the loss of metal ions. In this example, the composite framework iron-supported multi-scale molecular sieve composite nanofiber material was used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L of the composite framework iron-supported multi-scale molecular sieve nanocatalyst prepared in this example (i.e., the concentration of the molecular sieve nanocatalyst in the mixture was 0.2 g / L, the same below), 25 mL of freshly prepared 20 mmol / L hydrogen peroxide solution (i.e., the hydrogen peroxide solution was prepared and used immediately), and 55 mL of deionized water were added to a dry and clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. Finally, the degradation rate of methylene blue reached 95% (TOC conversion rate = 80%), and the iron ion leaching concentration in the composite framework iron-supported multi-scale molecular sieve nanocatalyst was less than 2 mg / L. Meanwhile, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached more than 90% (TOC conversion rate >70%), indicating that the catalyst has good stability.

[0076] Example 2

[0077] A method for preparing a composite framework copper-supported multi-scale molecular sieve nanocatalyst:

[0078] (1) Preparation of seed solution from seed gel

[0079] (1-1) Take out a dry and clean beaker, pour in 8.6g (0.0106mol) TPAOH (25wt.% aqueous solution) and 1.8g (0.0391mol) ETOH that have been weighed in advance, and then add 0.0986g (0.0004mol) CuSO4·5H2O as copper source to prepare skeletal copper. Place the beaker on a magnetic stirrer and add 9.88g (0.0474mol) TEOS dropwise while stirring.

[0080] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 24.52TPAOH / 110SiO2 / 835.72H2O / 90.62ETOH / 0.92Cu that can be used directly.

[0081] (2) Preparation of seed-supported glass fibers by impregnation method

[0082] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0324g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0083] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0084] (3) Preparation of composite framework copper-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0085] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven for steam-assisted crystallization at 150℃ for 24h;

[0086] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0087] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, and the composite framework copper-supported multi-scale molecular sieve nanocatalyst was obtained.

[0088] The composite framework copper-supported multi-scale molecular sieve composite nanofiber material has important applications in wastewater treatment. It can firmly support and reduce the loss of metal ions. The composite framework copper-supported multi-scale molecular sieve composite nanofiber material prepared in this example can be used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L catalyst, 25 mL of freshly prepared 20 mmol / L hydrogen peroxide solution, and 55 mL of deionized water were added to a dry and clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. The final determination showed that the degradation rate of methylene blue reached 95.8% (TOC conversion rate = 78.5%), and the copper ion leaching concentration was less than 1.97 mg / L. Furthermore, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached over 90% (TOC conversion rate > 70%), indicating that the catalyst has good stability.

[0089] Example 3

[0090] A method for preparing a composite framework cobalt-supported multi-scale molecular sieve nanocatalyst:

[0091] (1) Preparation of seed solution from seed gel

[0092] (1-1) Take out a dry and clean beaker, pour in 9.0g (0.0111mol) TPAOH (25wt.% aqueous solution) and 2.2g (0.0478mol) ETOH that have been weighed in advance, and then add 0.1111g (0.0004mol) CoSO4·7H2O as cobalt source to prepare skeletal cobalt. Place the beaker on a magnetic stirrer and add 9.88g (0.0474mol) TEOS dropwise while stirring.

[0093] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 25.66TPAOH / 110SiO2 / 876.21H2O / 110.75ETOH / 0.92Co that can be used directly.

[0094] (2) Preparation of seed-supported glass fibers by impregnation method

[0095] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0324g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0096] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0097] (3) Preparation of composite framework cobalt-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0098] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven for steam-assisted crystallization at 150℃ for 24h;

[0099] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0100] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, thus obtaining a composite framework cobalt-supported multi-scale molecular sieve nanocatalyst.

[0101] Cobalt-supported multi-scale molecular sieve composite nanofibers with a composite framework have important applications in wastewater treatment. They can firmly support and reduce the loss of metal ions. The cobalt-supported multi-scale molecular sieve composite nanofibers prepared in this example can be used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L catalyst, 25 mL of freshly prepared 20 mmol / L hydrogen peroxide solution, and 55 mL of deionized water were added to a dry, clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. The degradation rate of methylene blue reached 95.6% (TOC conversion = 80.2%), and the cobalt ion leaching concentration was less than 1.9 mg / L. Furthermore, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached over 90% (TOC conversion > 70%), indicating that the catalyst has good stability.

[0102] Example 4

[0103] A method for preparing composite framework iron-supported multi-scale molecular sieve nanocatalysts:

[0104] (1) Preparation of seed solution from seed gel

[0105] (1-1) Take out a dry and clean beaker, pour in 8.7g (0.0107mol) TPAOH (25wt.% aqueous solution) and 1.9g (0.0412mol) ETOH that have been weighed in advance, and then add 0.0934g (0.0004mol) FeCl2·6H2O as an iron source to prepare skeletal iron. Place the beaker on a magnetic stirrer and add 9.92g (0.0476mol) TEOS dropwise while stirring.

[0106] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 24.71TPAOH / 110SiO2 / 842.91H2O / 95.27ETOH / 0.92Fe that can be used directly.

[0107] (2) Preparation of seed-supported glass fibers by impregnation method

[0108] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0325g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0109] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0110] (3) Preparation of composite framework iron-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0111] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven for steam-assisted crystallization at 150℃ for 24h;

[0112] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0113] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, thus obtaining a composite framework iron-supported multi-scale molecular sieve nanocatalyst.

[0114] Composite framework iron-supported multi-scale molecular sieve composite nanofiber materials have important applications in wastewater treatment. They can firmly support and reduce the loss of metal ions. The composite framework iron-supported multi-scale molecular sieve composite nanofiber material prepared in this example can be used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L catalyst, 25 mL of freshly prepared 20 mmol / L hydrogen peroxide solution, and 55 mL of deionized water were added to a dry and clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. The final determination showed that the degradation rate of methylene blue reached 94.8% (TOC conversion rate = 80%), and the iron ion leaching concentration was less than 2.18 mg / L. Furthermore, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached over 90% (TOC conversion rate > 70%), indicating that the catalyst has good stability.

[0115] Example 5

[0116] A method for preparing a composite framework copper-supported multi-scale molecular sieve nanocatalyst:

[0117] (1) Preparation of seed solution from seed gel

[0118] (1-1) Take out a dry and clean beaker, pour in 8.75g (0.0108mol) TPAOH (25wt.% aqueous solution) and 1.83g (0.0391mol) ETOH that have been weighed in advance, and then add 0.0669g (0.0004mol) CuCl2·2H2O as copper source to prepare skeletal copper. Place the beaker on a magnetic stirrer and add 9.83g (0.0470mol) TEOS dropwise while stirring.

[0119] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 25.15TPAOH / 110SiO2 / 854.39H2O / 92.89ETOH / 0.92Cu that can be used directly.

[0120] (2) Preparation of seed-supported glass fibers by impregnation method

[0121] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0321g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0122] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0123] (3) Preparation of composite framework copper-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0124] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven for steam-assisted crystallization at 150℃ for 24h;

[0125] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0126] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, and the composite framework copper-supported multi-scale molecular sieve nanocatalyst was obtained.

[0127] The composite framework copper-supported multi-scale molecular sieve composite nanofiber material has important applications in wastewater treatment. It can firmly support and reduce the loss of metal ions. The composite framework copper-supported multi-scale molecular sieve composite nanofiber material prepared in this example can be used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L catalyst, 25 mL of 20 mmol / L freshly prepared hydrogen peroxide solution, and 55 mL of deionized water were added to a dry and clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. The final test showed that the degradation rate of methylene blue reached 95.5% (TOC conversion rate = 78.3%), and the copper ion leaching concentration was less than 2 mg / L. Furthermore, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached over 90% (TOC conversion rate > 70%), indicating that the catalyst has good stability.

[0128] Example 6

[0129] A method for preparing a composite framework cobalt-supported multi-scale molecular sieve nanocatalyst:

[0130] (1) Preparation of seed solution from seed gel

[0131] (1-1) Take out a dry and clean beaker, pour in 8.77g (0.0108mol) TPAOH (25wt.% aqueous solution) and 1.93g (0.0419mol) ETOH that have been weighed in advance, and then add 0.0945g (0.0004mol) CoCl2·6H2O as cobalt source to prepare skeletal cobalt. Place the beaker on a magnetic stirrer and add 9.91g (0.0476mol) TEOS dropwise while stirring.

[0132] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 24.93TPAOH / 110SiO2 / 850.47H2O / 96.87ETOH / 0.92Co that can be used directly.

[0133] (2) Preparation of seed-supported glass fibers by impregnation method

[0134] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0325g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0135] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0136] (3) Preparation of composite framework cobalt-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0137] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven for steam-assisted crystallization at 150℃ for 24h;

[0138] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0139] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, thus obtaining a composite framework cobalt-supported multi-scale molecular sieve nanocatalyst.

[0140] Cobalt-supported multi-scale molecular sieve composite nanofibers with a composite framework have important applications in wastewater treatment. They can firmly support and reduce the loss of metal ions. The cobalt-supported multi-scale molecular sieve composite nanofibers with a composite framework prepared in this example can be used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L catalyst, 25 mL of freshly prepared 20 mmol / L hydrogen peroxide solution, and 55 mL of deionized water were added to a dry and clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. The degradation rate of methylene blue was found to be 96.1% (TOC conversion rate = 77.3%), and the cobalt ion leaching concentration was less than 1.89 mg / L. Furthermore, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached over 90% (TOC conversion rate > 70%), indicating that the catalyst has good stability.

[0141] Example 7

[0142] A method for preparing a composite framework molybdenum-supported multi-scale molecular sieve nanocatalyst:

[0143] (1) Preparation of seed solution from seed gel

[0144] (1-1) Take out a dry and clean beaker, pour in 8.95g (0.0110mol) TPAOH (25wt.% aqueous solution) and 2.11g (0.0458mol) ETOH that have been weighed in advance, and then add 0.1086g (0.0004mol) MoCl3·6H2O as a molybdenum source to prepare skeletal molybdenum. Place the beaker on a magnetic stirrer and add 9.93g (0.0477mol) TEOS dropwise while stirring.

[0145] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 25.39TPAOH / 110SiO2 / 866.11H2O / 105.70ETOH / 0.92Mo that can be used directly.

[0146] (2) Preparation of seed-supported glass fibers by impregnation method

[0147] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0326g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0148] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0149] (3) Preparation of composite framework molybdenum-supported multi-scale molecular sieve catalysts by steam-assisted crystallization

[0150] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of the 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven for steam-assisted crystallization at 150℃ for 24h;

[0151] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0152] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, and the composite framework molybdenum supported multi-scale molecular sieve nanocatalyst was obtained.

[0153] The composite framework molybdenum-supported multi-scale molecular sieve composite nanofiber material has important applications in wastewater treatment. It can firmly support and reduce the loss of metal ions. The composite framework molybdenum-supported multi-scale molecular sieve composite nanofiber material prepared in this example can be used to catalyze the degradation of a methylene blue solution with an initial concentration of 10 mg / L. 20 mL of 50 mg / L methylene blue solution, 0.2 g / L catalyst, 25 mL of freshly prepared 20 mmol / L hydrogen peroxide solution, and 55 mL of deionized water were added to a dry and clean beaker to obtain 100 mL of mixture. The mixture was shaken at 200 rpm for 30 min. The final determination showed that the degradation rate of methylene blue reached 95.3% (TOC conversion rate = 79.3%), and the molybdenum ion leaching concentration was less than 1.96 mg / L. Furthermore, after drying the catalyst after the reaction, the experiment was repeated. After 5 cycles, the methylene blue degradation rate still reached over 90% (TOC conversion rate > 70%), indicating that the catalyst has good stability.

[0154] Comparative Example 1

[0155] Similar to Example 1, except that in step (2-1), quartz fibers are impregnated into the seed gel, i.e., in this comparative example, quartz fibers are used instead of glass fibers.

[0156] The results showed that, compared with Example 1, the framework iron-supported multi-scale molecular sieve nanocatalyst prepared in this comparative example had a degradation rate of 80% (TOC conversion = 53%) in the catalytic oxidation degradation of methylene blue under the same conditions, which was low.

[0157] Comparative Example 2

[0158] Same as Example 1, except that 0.0651g (0.0008mol) of NaAlO2 is added in step (2-1).

[0159] The results showed that the molecular sieve nanocatalyst prepared in this comparative example had a looser structure compared with that in Example 1.

[0160] The performance of the molecular sieve nanocatalyst prepared in this comparative example was tested in the same way as in Example 1. Compared with Example 1, the molecular sieve nanocatalyst prepared in this comparative example had a degradation rate of 83% (TOC conversion rate = 42.5%) in the catalytic oxidation degradation of methylene blue under the same conditions, which is low.

[0161] Comparative Example 3

[0162] Same as Example 1, except that FeSO4·7H2O is not introduced in step (1-1).

[0163] The results show that the multi-scale molecular sieve nanocatalyst prepared in this comparative example has uniform pores and high mechanical strength.

[0164] The performance of the molecular sieve nanocatalyst prepared in this comparative example was tested in the same way as in Example 1. Compared with Example 1, the molecular sieve nanocatalyst prepared in this comparative example had a degradation rate of 30% (TOC conversion = 7%) in the catalytic oxidation degradation of methylene blue under the same conditions, which is low.

[0165] Comparative Example 4: Traditional Impregnation Method

[0166] (1) Preparation of seed solution from seed gel

[0167] (1-1) Take out a dry and clean beaker, pour in 8.8g (0.0108mol) TPAOH (25wt.% aqueous solution) and 2g (0.0435mol) ETOH that have been weighed in advance, place the beaker on a magnetic stirrer, and add 9.92g (0.0476mol) TEOS dropwise while stirring;

[0168] (1-2) Take another dry and clean 100mL blue-mouth bottle, pour the mixture in the beaker into it, place the blue-mouth bottle on a magnetic stirrer and stir continuously for 6 hours, then put it in an oven with the temperature set to 100℃ and let it crystallize for 48 hours. After cooling, you will get a seed solution of 25TPAOH / 110SiO2 / 853.42H2O / 100ETOH that can be used directly.

[0169] (2) Preparation of seed-supported glass fibers by impregnation method

[0170] (2-1) Add 1g of deionized water to a dry and clean beaker, then add 0.0325g (0.0004mol) of NaAlO2, stir and mix with a glass rod, then add it to 12g of the above seed solution, stir, and use tweezers to immerse 0.5g of glass fiber into the above gel for 12h.

[0171] (2-2) Place the impregnated glass fiber into a centrifuge tube, then set the centrifuge speed to 6 r / s and the time to 1 min to centrifuge and remove excess seed crystals from the glass fiber cavities. Remove the glass fiber and dry it in an oven at 80℃ for 12 h.

[0172] (3) Preparation of multi-scale molecular sieve catalysts

[0173] (3-1) Tear the seeded glass fiber with tweezers and place it in a raised PTFE support, which is located in the middle of the PTFE liner of an 80mL reactor. Pour 4mL of distilled water into the bottom of the liner, and then place the liner in an oven to crystallize at 150℃ for 24h;

[0174] (3-2) After cooling to room temperature, dry the product at 110°C overnight;

[0175] (3-3) The temperature was raised to 500℃ in a muffle furnace at a rate of 1℃ / min, and calcined for 4h. Then the temperature was lowered to room temperature at the same rate to remove the organic template agent, thus obtaining a multi-scale molecular sieve nanocatalyst.

[0176] (4) Preparation of iron-supported multi-scale molecular sieve nanocatalysts

[0177] (4-1) Weigh 0.359 g of ferrous sulfate into a beaker, add deionized water and stir until completely dissolved. Transfer to a 100 mL volumetric flask for later use (concentration 2.36 × 10⁻⁶). -2 mol / L);

[0178] (4-2) Weigh 0.4875g of molecular sieve powder into a 250mL blue-mouth bottle, add 100mL of the above solution, sonicate for 30min, and then add 25mL of 0.5mol / L NaOH solution.

[0179] (4-3) The solution was shaken at 200 rpm for half an hour, filtered, and dried at 120℃ for 2 hours to obtain an iron-supported multi-scale molecular sieve composite nanocatalyst.

[0180] The performance of the iron-supported multi-scale molecular sieve nanocatalyst prepared in this comparative example was tested in the same way as in Example 1. Compared with Example 1, although the degradation rate of methylene blue in the catalytic oxidation degradation reaction under the same conditions reached 90%, the TOC conversion rate was only 56.3%, and the iron ion leaching concentration reached 20 mg / L. Furthermore, after 5 cycles, the methylene blue degradation rate decreased to 50%, and the TOC conversion rate was <10%.

[0181] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A preparation method of a composite framework metal-supported multi-scale molecular sieve nanocatalyst for methylene blue degradation, characterized in that, Includes the following steps: Tetrapropylammonium hydroxide was mixed with anhydrous ethanol, and a metal salt was added simultaneously. Then, a silicon source was added under stirring, and the mixture was crystallized to prepare a seed solution. Then, sodium aluminate solution is added to the seed solution, and the glass fiber is immersed in the seed solution containing sodium aluminate solution. After centrifugation and drying, the seed-loaded metal skeleton glass fiber is obtained. The seed-loaded metal skeleton glass fiber is subjected to steam-assisted crystallization. The product is dried, calcined, and ground to obtain the composite skeleton metal-supported multi-scale molecular sieve nanocatalyst for methylene blue degradation. The metal salt includes one of soluble iron salt, soluble copper salt, soluble cobalt salt, and soluble molybdenum salt; The molar ratio of tetrapropylammonium hydroxide, anhydrous ethanol and silicon source is 10:(10~50):(10~50). The crystallization temperature is 60~140℃, and the time is 30~60 h; The concentration of the sodium aluminate solution is 0.3~0.8 mol / L; The temperature for the steam-assisted crystallization is 110~200℃, and the time is 15~35 h; The calcination temperature is 450~700℃, and the time is 3~8 h; The molar ratio of the metal salt to the silicon source is (1:60) to (1:180).

2. The method for preparing the composite framework metal-supported multi-scale molecular sieve nanocatalyst for methylene blue degradation according to claim 1, characterized in that, The silicon source is silicon tetrachloride, silane, or tetraethyl orthosilicate.

3. The method for preparing the composite framework metal-supported multi-scale molecular sieve nanocatalyst for methylene blue degradation according to claim 1, characterized in that, The immersion time is 10-20 hours; and / or The centrifugation process is as follows: centrifugation at 5~8 r / s for 40~80 s.

4. A composite framework metal supported multi-scale molecular sieve nanocatalyst for methylene blue degradation, characterized in that, It is prepared according to any one of claims 1 to 3.

5. The application of the composite framework metal-supported multi-scale molecular sieve nanocatalyst for methylene blue degradation as described in claim 4 in the removal of methylene blue, a pollutant in water.

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