A method for synthesizing iron-doped hollow molecular sieve materials in a framework by ion exchange-assisted hydrothermal synthesis and application thereof

Abstract

The application discloses a preparation method of iron-doped framework hollow molecular sieve material synthesized by ion exchange assisted hydrothermal synthesis and application thereof, and belongs to the technical field of molecular sieves. The preparation method of the iron-doped framework hollow molecular sieve material is as follows: a silicon sol, sodium metaaluminate, sodium hydroxide, water and a soluble iron source are mixed, stirring and aging are performed until complete hydrolysis, and a synthesis liquid is obtained; a quartz fiber carrier is immersed in the synthesis liquid, reaction is carried out at 60-150 DEG C for 12-48 hours, and after cooling, washing and drying are performed. The iron-doped framework hollow molecular sieve material has the effects of resisting metal high-temperature sintering, inhibiting metal grain growth and maintaining high metal dispersity, and the framework iron has a more stable crystal structure than traditional impregnation methods, which is beneficial to ensuring that the catalyst remains stable and efficient during the reaction process, can reduce the possibility of side reactions and the leaching rate of the active component of the catalyst, and thus has better catalytic performance and a longer service life.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve technology, and particularly relates to a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis and its application. Background Technology

[0002] Public concern about water pollution treatment is gradually increasing. In order to build a resource-saving and environmentally friendly society and achieve sustainable development, it is necessary to comprehensively reduce wastewater discharge and solve water pollution problems in all aspects.

[0003] The textile printing and dyeing industry is one of the industrial sectors with the largest water consumption and wastewater discharge. Statistics show that printing and dyeing enterprises in my country discharge 3-4 million tons of wastewater daily. Textile industrial wastewater generally contains suspended solids, grease, fiber debris, surfactants, and various dyes. For example, cotton textile wastewater often contains cotton lint and sizing agents, while wool textile wastewater often contains grease; printing and dyeing wastewater often contains sizing agents, dyes, auxiliaries, and various organic substances. Textile wastewater is characterized by its large volume, complex composition, and heavy economic burden for treatment. Even after treatment, residues may still gradually accumulate in the natural environment. Currently, common textile wastewater treatment methods have certain limitations: biodegradation methods have limited applicability and are difficult to apply on a large scale; high-cost methods such as electrochemical and membrane filtration have unstable treatment efficiency and are not suitable for large-scale promotion. In contrast, adsorption and catalytic oxidation methods have attracted much attention due to their simplified processes and higher efficiency. Adsorbents, as the key foundation of adsorption methods, have already been used in textile wastewater treatment, but their activity and stability still have room for improvement.

[0004] To address these challenges, innovative and sustainable approaches are needed to improve wastewater treatment technologies in the textile printing and dyeing industry, in order to ensure the health of the ecological environment and the sustainable development of human society. Summary of the Invention

[0005] To address the problems of low efficiency, easy deactivation, difficult structural control, and difficult recycling of existing molecular sieves as catalysts, this invention proposes a method for the hydrothermal synthesis of iron-doped framework hollow molecular sieve materials using ion exchange-assisted methods, and its applications. Compared with conventional molecular sieve preparation methods, the novel iron-doped framework hollow molecular sieve material prepared by this invention directly uses untreated quartz fibers as raw materials, simplifying the preparation process. It eliminates the need for pretreatment with 3-aminopropyltrimethoxysilane (APTMS), toluene, etc., allowing for the formation of a dense molecular sieve membrane on the fiber surface. Furthermore, hydrothermal synthesis at a suitable temperature can control the agglomeration of particles on the molecular sieve surface, ultimately resulting in a stable hollow pore structure that significantly improves mass transfer efficiency, reduces leaching, and enhances material stability. Simultaneously, the iron-doped framework hollow molecular sieve material of this invention also possesses a large specific surface area, good thermal stability, and chemical stability. Combined with its structural properties, it can effectively exert its performance in fields such as wastewater treatment.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of the present invention:

[0008] This invention provides a method for the hydrothermal synthesis of iron-doped framework hollow molecular sieve materials using ion exchange-assisted synthesis, comprising the following steps:

[0009] The silica sol, sodium aluminate, sodium hydroxide, water and soluble iron source are mixed and stirred until completely hydrolyzed to obtain the synthetic solution.

[0010] The quartz fiber carrier is immersed in the synthesis solution (so that the quartz fiber and the synthesis solution can fully exchange ions, thereby making the iron skeleton in the molecular sieve material uniformly distributed), and reacted at 60-150℃ for 12-48 hours. After cooling, it is washed and dried to obtain the iron-doped hollow molecular sieve material.

[0011] The preparation steps of the synthetic solution are as follows: Sodium aluminate (NaAlO2), sodium hydroxide (NaOH) and soluble iron source are mixed, water is added, and the mixture is stirred until a clear and transparent solution is obtained. Silica sol is added while stirring, and the mixture is stirred and aged until it is completely hydrolyzed to obtain the synthetic solution.

[0012] The mass ratio of the silica sol, sodium aluminate, sodium hydroxide, water, and soluble iron source is (5.00-10.00):(2.00-6.80):(20.00-55.00):(190.00-260.00):(3.80-9.00).

[0013] Preferably, the mass ratio of the silica sol, sodium aluminate, sodium hydroxide, water, and soluble iron source is (8.00-10.00):(2.00-4.00):(48.00-55.00):(200.00-240.00):(3.80-5.20), (5.00-8.00):(5.00-6.80):(20.00-30.00):(200.00-260.00):(4.00-5.50), or (5.00-10.00):(3.50-4.70):(35.00-44.00):(190.00-260.00):(6.00-9.00). This invention, through investigation of different mass ratios of silica sol, sodium aluminate, sodium hydroxide, water, and soluble iron source, discovered that iron-framework hollow molecular sieve materials synthesized at specific mass ratios exhibit superior morphology and performance. Taking the silica-alumina ratio in the molecular sieve synthesis solution as an example, a ratio that is too low will cause the molecular sieve grains to grow excessively and will generate impurities of other molecular sieve crystal types (such as type A molecular sieves), while a ratio that is too high will easily generate impurities such as mesoporous molecular sieve crystals and type P molecular sieves, and will be unable to form a dense iron-framework molecular sieve structure, thus leading to a significant decrease in molecular sieve performance.

[0014] For example, the soluble iron source is FeSO4·7H2O.

[0015] The drying temperature is 100-150℃, and the time is 12-48 hours.

[0016] Octahedral zeolite molecular sieves, due to their well-developed three-dimensional pore system and large pore volume, have important applications in adsorption, separation, and catalysis. As a six-membered ring molecular sieve with silica and alumina, its basic structural unit is similar to the crystal structure of diamond. Generally, those with a Si / Al ratio between 1 and 1.5 are called X-type molecular sieves, and those with a Si / Al ratio greater than 1.5 are called Y-type molecular sieves. Both low-silica X-type and high-silica Y-type molecular sieves are major components of the most widely used petroleum processing catalysts, and they are also important adsorbents used for gas adsorption, separation, and purification. Octahedral zeolite molecular sieves possess structural advantages such as high temperature resistance, resistance to chemical and biological corrosion, good mechanical strength and catalytic performance, and a regular pore structure. Compared to NaA-type and MFI-type molecular sieves, octahedral zeolite molecular sieves have larger pore sizes and a three-dimensional cage-like pore structure, thus achieving greater separation selectivity and permeation flux. Due to the presence of metal elements in the molecular sieve framework, octahedral zeolite molecular sieve frameworks contain cations with balanced charges (such as Na+). + This characteristic gives it unique and excellent performance in ion exchange, catalysis, and adsorption. Furthermore, the high metal element content in the octahedral zeolite molecular sieve framework and the highly dispersed Na in the cages contribute to its superior properties. +This gives it high polarity, allowing for the selective adsorption and separation of polar molecules. This invention successfully incorporates iron into the molecular sieve framework structure during preparation using a hydrothermal synthesis combined with ion exchange, partially replacing aluminum, thereby controlling the surface properties of the catalyst support. Compared with common impregnation techniques, the iron-doped framework molecular sieve prepared by the ion exchange method in this invention not only resists high-temperature metal sintering, inhibits metal grain growth, and maintains high metal dispersion, but also possesses a more stable crystal structure than traditional impregnation methods. This ensures the catalyst remains stable and efficient during the reaction, reduces the possibility of side reactions and the leaching rate of the active catalyst components, resulting in better catalytic performance and a longer service life.

[0017] Hollow molecular sieves possess a unique hollow pore structure. When used as adsorbents, catalysts, or catalyst supports, especially in reactions involving macromolecules, their hollow pore structure provides convenient fluid channels, facilitating the transfer of reactants and products and improving contact efficiency. Simultaneously, combined with the microporous structure inherent in the molecular sieve itself and the mesoporous structure formed by grain stacking, the hierarchical pore structure of hollow molecular sieves can control diffusion path length and reduce leakage of active components, while inhibiting coke deposition during the reaction process, thereby improving catalyst stability and selectivity and extending service life. This invention, through continuous optimization of the preparation process, combines the advantages of octahedral zeolite-type iron-doped framework molecular sieve materials with those of hollow molecular sieves. The resulting hollow iron-doped framework molecular sieve material exhibits strong adsorption performance, good stability, low preparation cost, high mechanical strength, and large specific surface area, demonstrating better catalytic performance and service life compared to general catalysts. Based on the needs of textile dyeing and printing organic wastewater treatment technology, the iron-doped framework hollow molecular sieve material prepared in this invention can be combined with catalytic wet hydrogen peroxide (CWPO) technology to further expand its application prospects in the field of industrial wastewater degradation.

[0018] The second technical solution of the present invention:

[0019] This invention provides an iron-doped hollow molecular sieve material prepared according to the above method.

[0020] The iron-doped hollow molecular sieve material prepared by this invention is a novel iron-doped hollow molecular sieve material with a stable hollow structure. This structure can reduce resistance, facilitate the transfer of reactants and products, reduce the occurrence of side reactions and the leaching of active components of the catalyst, and has better catalytic performance and longer service life.

[0021] The third technical solution of the present invention:

[0022] The present invention also provides the application of the iron-doped hollow molecular sieve material in the treatment of organic wastewater from textile printing and dyeing.

[0023] The fourth technical solution of the present invention:

[0024] The present invention also provides a method for treating organic wastewater from textile printing and dyeing, wherein the iron-doped hollow molecular sieve material is added to the organic wastewater and reacted continuously at 30-60°C for 3 hours.

[0025] Preferably, in the method for treating organic wastewater from textile printing and dyeing, the amount of iron-doped hollow molecular sieve material used is 2.0 g / L (i.e., 2.0 g of iron-doped hollow molecular sieve material is contained in each liter of organic wastewater from textile printing and dyeing).

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] (1) The novel iron-doped hollow molecular sieve material prepared by this invention has a stable hollow structure. This structure can reduce resistance, facilitate the transfer of reactants and products, reduce the occurrence of side reactions and the leaching of active components of the catalyst, and has better catalytic performance and longer service life.

[0028] (2) The novel iron-doped hollow molecular sieve material prepared by this invention has a unique hollow fiber structure. Compared with commonly used molecular sieves, it has advantages such as large specific surface area, good thermal stability and chemical stability. It can effectively exert its performance in the fields of sewage treatment, so that no toxic and harmful by-products are produced throughout the reaction process, thereby realizing the green and efficient conversion of sewage.

[0029] (3) The process of preparing novel iron-doped hollow molecular sieve materials is simple and does not require pretreatment of quartz fibers. This helps to simplify the preparation process, control the structure of the finished product and reduce the preparation cost, thereby improving the application prospects of octahedral zeolite molecular sieves in the industrial field. Attached Figure Description

[0030] 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:

[0031] Figure 1 The image shows an electron microscope (EM) image of the cross-section of the molecular sieve material prepared in Example 1.

[0032] Figure 2 The image shows an electron microscope (EM) image of the fiber surface of the molecular sieve material prepared in Example 1.

[0033] Figure 3 The image shows the energy-dispersive X-ray spectrum of the molecular sieve material prepared in Example 1. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0040] All raw materials used in the embodiments of this invention were purchased commercially. As an example, silica sol was purchased from Shanghai Huicheng Biotechnology Co., Ltd.; and quartz fiber was purchased from Shanghai Xinhu Experimental Equipment Co., Ltd.

[0041] In this invention, when calculating the methylene blue degradation rate, 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%.

[0042] In this invention, the leaching rate of the active component of the chemical agent is calculated as follows: metal concentration of the active component in the solution after reaction (g / L) × solution volume (L) / (mass fraction of the active component metal in the material (obtained by the mass ratio of the material preparation) × material addition concentration (g / L) × solution volume (L)) × 100%.

[0043] In some embodiments of the present invention, a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis is provided, comprising the following steps:

[0044] Sodium aluminate, sodium hydroxide and soluble iron source are mixed, water is added and stirred until a clear and transparent solution is obtained. Silica sol is added while stirring and the mixture is stirred and aged until it is completely hydrolyzed to obtain the synthetic solution.

[0045] The quartz fiber carrier is immersed in the synthesis solution and reacted at 60-150℃ for 12-48 hours. After cooling, it is washed and dried to obtain the iron-doped hollow molecular sieve material.

[0046] In some embodiments of the present invention, the mass ratio of silica sol, sodium aluminate, sodium hydroxide, water and soluble iron source is (5.00-10.00):(2.00-6.80):(20.00-55.00):(190.00-260.00):(3.80-9.00). For example, the mass ratio of silica sol, sodium aluminate, sodium hydroxide, water, and soluble iron source can be (8.00-10.00):(2.00-4.00):(48.00-55.00):(200.00-240.00):(3.80-5.20), (5.00-8.00):(5.00-6.80):(20.00-30.00):(200.00-260.00):(4.00-5.50), or (5.00-10.00):(3.50-4.70):(35.00-44.00):(190.00-260.00):(6.00-9.00).

[0047] In some embodiments of the present invention, the soluble iron source is FeSO4·7H2O.

[0048] In some embodiments of the present invention, the drying temperature is 100-150°C and the time is 12-48 hours.

[0049] The novel iron-doped hollow molecular sieve prepared using the method of this invention possesses a large specific surface area, uniform pore structure, and good thermal and mechanical stability, making it applicable in various fields such as adsorption separation, membrane reactions, catalysis, and sensors. The hollow pore structure helps shorten diffusion paths, improve conduction efficiency, and reduce particle leaching, thereby enhancing the stability and selectivity of the material and improving wastewater purification efficiency. This allows for innovative applications in wastewater treatment.

[0050] Compared with MFI molecular sieve preparation methods, this invention does not require pre-preparation of seed crystals and can be directly converted, which is convenient and fast. Furthermore, compared with other octahedral zeolite-type molecular sieve conversion preparation methods, this invention, due to the addition of iron to increase polarity, can directly use untreated quartz fibers as raw materials, simplifying the preparation process. It eliminates the need for pretreatment with 3-aminopropyltrimethoxysilane (APTMS), toluene, etc., to form a dense molecular sieve membrane on the fiber surface. Hydrothermal synthesis at a suitable temperature can control the clustering of particles on the molecular sieve surface, ultimately giving the material a stable hollow pore structure, significantly improving mass transfer efficiency, reducing leaching, and enhancing material stability.

[0051] This invention yields an octahedral zeolite-type molecular sieve. As a six-membered ring molecular sieve of silica and alumina, its basic structural unit is similar to the crystal structure of diamond. Due to the presence of metal elements in the molecular sieve framework, the molecular sieve framework prepared by this invention contains cations with balanced charges (such as Na). + This characteristic gives the material more acidic and active sites, and more structural defects, which allows it to better bind with reactants in the reaction and exhibit unique and excellent performance in catalysis and adsorption.

[0052] The octahedral zeolite molecular sieve obtained in this invention has a larger pore size and a three-dimensional cage-like channel structure compared to ZSM-5 (MFI molecular sieve), thus achieving greater separation selectivity and permeation flux. Furthermore, the high metal element content in the octahedral zeolite molecular sieve framework and the highly dispersed Na in the cages contribute to its superior performance. + This gives it high polarity, allowing for the selective adsorption and separation of polar molecules.

[0053] To address the problem that iron loaded onto the surface of molecular sieves via impregnation readily forms oxides with air, reducing the surface charge and acidity of the catalyst, this invention introduces iron into the molecular sieve framework during preparation. Iron exists in ionic or atomic form within the framework, partially replacing aluminum and forming chemical bonds with other atoms (such as Si and O). By controlling the iron content in the framework, the surface properties of the catalyst support are modulated, resulting in a stronger overall charge on the catalyst material, which is beneficial for catalytic reactions.

[0054] Catalysts prepared by impregnation or ion exchange have their active component, iron, located on the surface of the molecular sieve. This iron has weak interaction with the support and is prone to detachment during the reaction, leading to rapid catalyst deactivation and the risk of secondary contamination. Compared to common impregnation techniques, the iron-doped framework molecular sieve prepared by the ion exchange method in this invention not only resists high-temperature metal sintering, inhibits metal grain growth, and maintains high metal dispersion, but also features a more stable crystal structure in the framework iron compared to traditional impregnation methods. This ensures the catalyst remains stable and efficient during the reaction, reduces the possibility of side reactions and the leaching rate of the active component, resulting in better catalytic performance and a longer service life.

[0055] The iron-doped hollow molecular sieve material prepared by this invention can be used to treat organic wastewater from textile printing and dyeing. In the embodiments of this invention, wastewater containing methylene blue is used as an example.

[0056] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0057] The technical solution of the present invention will be further illustrated by the following embodiments.

[0058] Example 1

[0059] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0060] (1) Place 51.50g NaOH, 3.00g NaAlO2 and 4.50g FeSO4·7H2O in a beaker, add 220.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 9.00g silica sol. After stirring and aging the resulting solution for 1.5 hours, the synthesis solution is obtained.

[0061] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.3g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 65°C for 24 hours.

[0062] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0063] (4) The washed solid was placed in an oven and dried at 120°C for 24 hours to obtain a novel iron-doped hollow molecular sieve.

[0064] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration was 2.5 mg / L, hydrogen peroxide solution concentration was 5 mmol / L, catalyst (i.e., the novel iron-doped hollow molecular sieve, hereinafter the same) dosage was 2 g / L, and the reaction was carried out continuously at 30°C for 3 h. The methylene blue degradation efficiency remained above 96%, and the leaching rate of the active component of the catalyst was 1.2%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0065] from Figure 1 and Figure 2 As can be seen, the iron-framework molecular sieve material prepared by this invention exhibits a hollow structure overall, with relatively small and uniformly distributed molecular sieve grains. The molecular sieve grains are densely stacked to form a self-supporting tubular structure. The molecular sieve crystals themselves possess a three-dimensional cage-like microporous structure, while the stacked grains form a mesoporous structure. Combined with the macroporous structure of the hollow tubular structure, this multi-scale pore structure allows for the simultaneous achievement of high separation selectivity and permeation flux. Furthermore, the high metal element content in the molecular sieve framework and the highly dispersed Na in the cages contribute to its superior performance. + This gives it high polarity, allowing for the selective adsorption and separation of polar molecules.

[0066] The energy-dispersive X-ray spectrum of the molecular sieve material prepared in Example 1 is shown below. Figure 3 It can be seen that the molecular sieve exhibits a strong Fe element signal and the iron element is uniformly distributed in the molecular sieve framework. During the preparation of the molecular sieve, iron element is introduced into the molecular sieve framework structure. The iron element exists in the molecular sieve framework in the form of ions or atoms, partially replacing the aluminum element and forming chemical bonds with other atoms in the framework (such as Si, O, etc.). Therefore, it can be uniformly dispersed and remain stable during use, reducing leaching. This results in a stronger overall charge on the catalyst material, which is beneficial to the catalytic reaction.

[0067] Electron microscopy and energy-dispersive X-ray spectroscopy reveal that the hollow molecular sieve material prepared by the method of this invention has a uniform grain distribution and relatively small grain size, which is beneficial for improving the resistance of the molecular sieve material to high-temperature metal sintering.

[0068] Example 2

[0069] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0070] (1) Place 48.00g NaOH, 2.00g NaAlO2 and 3.80g FeSO4·7H2O in a beaker, add 200.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 8.00g silica sol. After stirring and aging the resulting solution for 2 hours, the synthesis solution is obtained.

[0071] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.3g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 60℃ for 48 hours.

[0072] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0073] (4) The washed solid is placed in an oven and dried at 110°C for 48 hours to obtain a novel iron-doped hollow molecular sieve.

[0074] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 30°C for 3 h. The methylene blue degradation efficiency remained above 95%, and the leaching rate of the active catalyst component was 1.0%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0075] Example 3

[0076] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0077] (1) Place 55.00g NaOH, 4.00g NaAlO2 and 5.20g FeSO4·7H2O in a beaker, add 240.0g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 10.00g silica sol. After stirring and aging the resulting solution for 1 hour, the synthesis solution is obtained.

[0078] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.3g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 70°C for 24 hours.

[0079] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0080] (4) The washed solid is placed in an oven and dried at 120°C for 24 hours to obtain a novel iron-doped hollow molecular sieve.

[0081] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 30°C for 3 h. The methylene blue degradation efficiency remained above 97%, and the leaching rate of the catalyst active component was 1.5%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0082] Example 4

[0083] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0084] (1) Place 25.00g NaOH, 5.90g NaAlO2 and 4.75g FeSO4·7H2O in a beaker, add 200.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 6.50g silica sol. After stirring and aging the resulting solution for 4 hours, the synthesis solution is obtained.

[0085] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.1g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 100℃ for 16 hours.

[0086] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0087] (4) The washed solid is placed in an oven and dried at 120°C for 36 hours to obtain a novel iron-doped hollow molecular sieve.

[0088] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 40°C for 3 h. The methylene blue degradation efficiency remained above 97%, and the leaching rate of the active catalyst component was 1.3%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0089] Example 5

[0090] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0091] (1) Place 20.00g NaOH, 5.00g NaAlO2 and 4.00g FeSO4·7H2O in a beaker, add 180.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 5.00g silica sol. After stirring and aging the resulting solution for 3 hours, the synthesis solution is obtained.

[0092] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.1g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 80℃ for 24 hours.

[0093] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0094] (4) The washed solid is placed in an oven and dried at 100°C for 48 hours to obtain a novel iron-doped hollow molecular sieve.

[0095] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 40°C for 3 h. The methylene blue degradation efficiency remained above 95%, and the leaching rate of the active catalyst component was 1.0%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0096] Example 6

[0097] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0098] (1) Place 30.00g NaOH, 6.80g NaAlO2 and 5.50g FeSO4·7H2O in a beaker, add 220.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 8.00g silica sol. After stirring and aging the resulting solution for 5 hours, the synthesis solution is obtained.

[0099] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.1g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 140℃ for 12 hours.

[0100] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0101] (4) The washed solid is placed in an oven and dried at 150°C for 24 hours to obtain a novel iron-doped hollow molecular sieve.

[0102] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 40°C for 3 h. The methylene blue degradation efficiency remained above 97%, and the leaching rate of the active catalyst component was 1.6%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0103] Example 7

[0104] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0105] (1) Place 39.50g NaOH, 4.10g NaAlO2 and 7.50g FeSO4·7H2O in a beaker, add 225.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 7.5g silica sol. After stirring and aging the resulting solution for 2 hours, the synthesis solution is obtained.

[0106] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.2g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 125℃ for 30 hours.

[0107] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0108] (4) The washed solid is placed in an oven and dried at 130°C for 15 hours to obtain a novel iron-doped hollow molecular sieve.

[0109] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 60°C for 3 h. The methylene blue degradation efficiency remained above 99%, and the leaching rate of the catalyst active component was 2.0%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0110] Example 8

[0111] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0112] (1) Place 35.00g NaOH, 3.50g NaAlO2 and 6.00g FeSO4·7H2O in a beaker, add 190.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 5g silica sol. After stirring and aging the resulting solution for 1 hour, the synthesis solution is obtained.

[0113] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.2g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 100℃ for 48 hours.

[0114] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0115] (4) The washed solid is placed in an oven and dried at 120°C for 24 hours to obtain a novel iron-doped hollow molecular sieve.

[0116] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 60°C for 3 h. The methylene blue degradation efficiency remained above 98%, and the leaching rate of the active catalyst component was 1.4%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0117] Example 9

[0118] This embodiment provides a method for synthesizing iron-doped framework hollow molecular sieve materials using ion exchange-assisted hydrothermal synthesis:

[0119] (1) Place 44.00g NaOH, 4.70g NaAlO2 and 9.00g FeSO4·7H2O in a beaker, add 260.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 10g silica sol. After stirring and aging the resulting solution for 3 hours, the synthesis solution is obtained.

[0120] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.2g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 150℃ for 24 hours.

[0121] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0122] (4) The washed solid is placed in an oven and dried at 140°C for 12 hours to obtain a novel iron-doped hollow molecular sieve.

[0123] The performance of the novel iron-doped hollow molecular sieve material prepared in this embodiment was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 60°C for 3 h. The methylene blue degradation efficiency remained above 99%, and the leaching rate of the active catalyst component was 2.7%. The novel iron-doped hollow molecular sieve material prepared in this embodiment has good catalytic degradation performance.

[0124] Comparative Example 1

[0125] Same as Example 7, except that FeSO4·7H2O was not added in step (1), that is, the molecular sieve material prepared in this comparative example is undoped with iron.

[0126] The performance of the iron-free molecular sieve material prepared in this comparative example was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst (i.e., iron-free molecular sieve material) dosage of 2 g / L, continuous reaction at 60℃ for 3 h, and the methylene blue degradation efficiency remained at about 50%.

[0127] Comparative Example 2 without silica sol

[0128] (1) Place 48.00g NaOH, 2.00g NaAlO2 and 3.80g FeSO4·7H2O in a beaker, add 200.00g deionized water, mix and stir with a magnetic stirrer. After stirring and aging the resulting solution for 2 hours, the synthesis solution is obtained.

[0129] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.3g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 60℃ for 48 hours.

[0130] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0131] (4) The washed solid was placed in an oven and dried at 110°C for 48 hours. It was found that no shaped molecular sieve material could be obtained.

[0132] Reasons for the failure of Comparative Example 2: Silica sol is a high-quality silicon source for synthesizing iron-framework molecular sieves. Molecular sieves synthesized using silica sol have high crystallinity, regular morphology, and good dispersibility, exhibiting excellent catalytic performance. Silica sol can provide framework structure and active centers during molecular sieve synthesis, and the morphology and pore structure of the molecular sieve can be controlled by adjusting the properties and amount of silica sol. The only difference between Comparative Example 2 and Example 2 is that silica sol was not added in step (1), resulting in the lack of molecular sieve framework structure and thus the inability to form molecular sieve material.

[0133] Comparative Example 3

[0134] Similar to Example 1, the difference is that FeSO4·7H2O was not added in step (1), but iron species were loaded in step (4) using a common impregnation technique. The specific method is as follows:

[0135] (1) Place 51.50g NaOH and 3.00g NaAlO2 in a beaker, add 220.00g deionized water, mix and stir with a magnetic stirrer until a clear and transparent solution is obtained. While stirring, add 9.00g silica sol. After stirring and aging the resulting solution for 1.5 hours, the synthesis solution is obtained.

[0136] (2) The obtained synthesis solution was transferred to the polytetrafluoroethylene liner of a 200mL stainless steel reactor, and 0.3g of quartz fiber carrier was immersed in the synthesis solution. The reactor was then placed in an oven and reacted at 65°C for 24 hours.

[0137] (3) After removing the stainless steel reactor, cool it to room temperature, remove the solids inside and wash it with deionized water;

[0138] (4) Add the washed solid and 4.50g FeSO4·7H2O into the blue-mouth bottle and add deionized water to 50mL. Then place the blue-mouth bottle in a shaker at 200rpm and shake for 1h.

[0139] (5) Take out the solid from the blue bottle and wash it with deionized water. Put the washed solid into an oven and dry it at 120°C for 24 hours to obtain the iron-supported molecular sieve prepared by common impregnation technology.

[0140] The performance of the iron-supported molecular sieve material prepared in this comparative example was tested under the following conditions: methylene blue solution concentration of 2.5 mg / L, hydrogen peroxide solution concentration of 5 mmol / L, catalyst dosage of 2 g / L, and continuous reaction at 30℃ for 3 h. The methylene blue degradation efficiency remained at about 85%, but after a period of use, the catalyst efficiency decreased significantly, and the leaching rate of active components reached more than 20%.

[0141] The reasons for the performance degradation and poor stability of Comparative Example 3: The iron-doped framework molecular sieve prepared by the ion exchange method not only resists high-temperature metal sintering, inhibits metal grain growth, and maintains high metal dispersion, but also has a more stable crystal structure than that prepared by common impregnation methods, which helps ensure the catalyst remains stable and efficient during the reaction. In contrast, the iron-supported molecular sieve prepared by this comparative example using common impregnation techniques has a poor loading effect, resulting in significantly lower catalytic degradation performance because only a portion of the iron species are loaded inside and on the surface of the molecular sieve during the impregnation process. Furthermore, the interaction between the active component and the support is weak, making it prone to detachment during the reaction, leading to loss of the active component, poor catalyst stability, and the risk of secondary pollution.

[0142] 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. The application of an iron-doped hollow molecular sieve material in the treatment of organic wastewater from textile printing and dyeing, characterized in that, The iron-doped framework hollow molecular sieve material is synthesized using ion exchange-assisted hydrothermal synthesis, including the following steps: The silica sol, sodium aluminate, sodium hydroxide, water and soluble iron source are mixed and stirred until completely hydrolyzed to obtain the synthetic solution. Untreated quartz fiber carrier is immersed in the synthesis solution and reacted at 60-150℃ for 12-48 hours. After cooling, it is washed and dried to obtain the iron-doped framework hollow molecular sieve material. The preparation steps of the synthetic solution are as follows: Sodium aluminate, sodium hydroxide and soluble iron source are mixed, water is added, and the mixture is stirred until a clear and transparent solution is obtained. Silica sol is added while stirring, and the mixture is stirred and aged until it is completely hydrolyzed to obtain the synthetic solution. The mass ratio of the silica sol, sodium aluminate, sodium hydroxide, water, and soluble iron source is (5.00-10.00): (2.00-6.80): (20.00-55.00): (190.00-260.00): (3.80-9.00).

2. The application according to claim 1, characterized in that, The mass ratio of the silica sol, sodium aluminate, sodium hydroxide, water, and soluble iron source is (8.00-10.00):(2.00-4.00):(48.00-55.00):(200.00-240.00):(3.80-5.20), (5.00-8.00):(5.00-6.80):(20.00-30.00):(200.00-260.00):(4.00-5.50), or (5.00-10.00):(3.50-4.70):(35.00-44.00):(190.00-260.00):(6.00-9.00).

3. The application according to claim 2, characterized in that, The soluble iron source is FeSO4·7H2O.

4. The application according to claim 1, characterized in that, The drying temperature is 100-150℃, and the time is 12-48 hours.

5. A method for treating organic wastewater from textile printing and dyeing, characterized in that, Iron-doped hollow molecular sieve material as described in claim 1 is added to textile dyeing and printing organic wastewater, and the mixture is continuously reacted at 30-60℃ for 3 hours.

6. The method for treating organic wastewater from textile printing and dyeing according to claim 5, characterized in that, The amount of iron-doped hollow molecular sieve material used is 2 g / L.

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