Preparation method and application of micro-mesoporous composite zeolite molecular sieve for efficient physical adsorption of gaseous iodine

Abstract

This invention relates to the field of zeolite molecular sieve technology, and discloses a method for preparing a highly efficient mesoporous-microporous composite zeolite molecular sieve for physical adsorption of gaseous iodine and its application. The preparation method is as follows: S1: Mix and stir a silicon source, a template agent, and a photoacid-generating agent PAG to obtain a coating solution; S2: Apply the coating solution evenly to a substrate to form a liquid film; S3: Irradiate the liquid film with a high-pressure mercury lamp of full wavelength for 30 minutes to obtain a mesoporous molecular sieve membrane containing a template agent; S4: Combine the mesoporous molecular sieve membrane with TPA... + S5: Grind NH4F in a mortar to obtain a viscous substance; S6: Crystallize the viscous substance to obtain a solid powder; S7: Calcine the solid powder in a muffle furnace to remove the template agent, obtaining a mesoporous composite zeolite molecular sieve. This invention is simple to operate, has high crystallinity and adjustable pore size, and can maintain a stable adsorption capacity at medium and low temperatures. It is an efficient and controllable green preparation technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of zeolite molecular sieve, in particular to a preparation method of a meso-microporous composite zeolite molecular sieve for efficiently physically adsorbing gaseous iodine and application thereof. BACKGROUND

[0002] Energy shortage has always been a topic of concern, and nuclear energy is an important part of solving energy shortage. However, with the development of nuclear industry, a large amount of nuclear waste is discharged, causing great damage to the environment. The nuclear waste includes a large amount of unused uranium resources, solid and radioactive elements produced by nuclear fission. The treatment of nuclear waste is not only for resource recycling but also for environmental protection. However, a large amount of radioactive iodine (I and I) will be produced in the reprocessing process, which has a long half-life and releases a large amount of γ rays in the decay process, causing harm to the human body. Therefore, capturing and storing gaseous iodine from waste has become an indispensable part of the development of nuclear industry. 131 I and 129 I), which has a long half-life, releases a large amount of γ rays in the decay process, causing harm to the human body. Therefore, capturing and storing gaseous iodine from waste has become an indispensable part of the development of nuclear industry.

[0003] At present, solution washing method and solid adsorbent method are two methods commonly used for capturing and storing gaseous iodine. The solution washing method uses a very corrosive solution to wash the waste gas containing iodine, which is self-evident in terms of environmental damage and danger. The solid adsorbent has the advantages of convenient use, simple preparation and low price, and is studied by scholars at home and abroad. The solid adsorbent for adsorbing gaseous iodine mainly includes aerogel, zeolite, covalent organic framework, metal organic framework, etc., which all have high specific surface area and rich pore structure, etc., which has great advantages in capturing radioactive iodine. However, due to the influence of the pore, the physical adsorption of iodine is limited, and only by introducing metals and changing the size of the pore can a higher iodine adsorption capacity be obtained. Zeolite is rich in microporous channels and is one of the materials with high iodine adsorption capacity.

[0004] So far, silver-containing zeolite has been widely used in the treatment of nuclear waste and nuclear accidents. However, silver, as a noble metal in transition metals, makes it not favored by industrial production. In recent years, zeolite coated with metal has been widely studied in the field of iodine adsorption, among which copper-based and bismuth-based zeolites can provide relatively stable adsorption sites. However, bismuth has low storage capacity, is radioactive and mainly chemisorbs gaseous iodine, which is difficult to commercialize. Copper not only has low price but also has large storage capacity, and is the most likely adsorbent to replace silver zeolite among many metals. However, most of the zeolites are loaded with metals by grafting, which not only has a small amount of loaded metal, but also is complicated and time-consuming. Moreover, the participation of metals is mainly chemical adsorption, which has poor recycling rate, while most of the adsorption of gaseous iodine relies on the pores of the adsorbent, i.e. physical adsorption. The chemical adsorption involving metals only accounts for a small part of the adsorption of the adsorbent.

[0005] At present, the material synthesized by pure silicon zeolite has all micropore channel structure. The all micropore is slow for the adsorption rate of gaseous iodine, and the mesopore is weak for the force of gaseous iodine, and the meso-micropore complex can make up for the deficiency of the two channels. Therefore, the controllable synthesis of meso-micropore complex zeolite molecular sieve, which has high efficient adsorption capacity for volatile iodine and can be reused, is the key to the synthesis of zeolite molecular sieve. SUMMARY

[0006] The purpose of the application: in view of the problems existing in the prior art, the application provides a preparation method of meso-micropore complex zeolite molecular sieve for efficient physical adsorption of gaseous iodine and application thereof. The meso-micropore complex zeolite molecular sieve is synthesized by crystallizing and recrystallizing the precursor SBA-15 amorphous molecular sieve and the template TPAOH at a certain temperature, introducing micropores under a certain mesopore, and converting the amorphous molecular sieve into zeolite molecular sieve, so that the highly crystalline meso-micropore zeolite molecular sieve is synthesized in one step. The application has the advantages of simple operation, high crystallinity, adjustable pore size, stable adsorption capacity at low temperature, and is a kind of efficient and controllable green preparation technology.

[0007] Technical scheme: the application provides a preparation method of meso-micropore complex zeolite molecular sieve for efficient physical adsorption of gaseous iodine, comprising the following steps:

[0008] S1: adding a silicon source, a template P123 and a photoacid generator PAG into a brown bottle, mixing and stirring uniformly to obtain a coating solution;

[0009] S2: uniformly smearing the coating solution on a substrate to form a liquid film;

[0010] S3: irradiating the liquid film coated on the substrate with a full-wavelength high-pressure mercury lamp for photo reaction for 30 min to obtain a mesoporous molecular sieve film containing the template;

[0011] S4: putting the mesoporous molecular sieve film, TPA + , NH4F into a mortar and grinding until a viscous substance is obtained;

[0012] S5: putting the viscous substance into a hydrothermal reaction kettle, crystallizing at 70-100 DEG C for 1-3 days, then crystallizing at 120-170 DEG C for 1-3 days, washing and drying to obtain a solid powder;

[0013] S6: putting the solid powder into a muffle furnace to calcine and remove the template to obtain a meso-micropore complex zeolite molecular sieve.

[0014] Further, in S4, the mass ratio of the mesoporous molecular sieve film, TPA + , NH4F is 1:0.5-2:0.2-1.

[0015] Further, the TPA+ TPAOH is 10%-50%.

[0016] Further, in S4, the water content of the viscous substance is 1%-5%.

[0017] Further, in S1, the mass ratio of the silicon source, the template agent P123 and the photoacid generator PAG is 1:0.6:0.03.

[0018] Further, the silicon source is PDMOS.

[0019] Further, the template agent P123 is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.

[0020] Further, the photoacid generator PAG is diphenyliodonium hexafluorophosphate.

[0021] Further, in S6, the specific conditions of the calcination are as follows:

[0022] The temperature is increased to 450-600 DEG C at a temperature increasing rate of 1-5 DEG C / min, and the calcination is performed for 5-8 h.

[0023] The application also provides a use of the meso-microporous composite zeolite molecular sieve prepared by the method in physical adsorption of gaseous iodine.

[0024] Beneficial effects: The application proposes a one-step solvent-free synthesis of meso-microporous composite zeolite molecular sieve, and the use of the pre-polymer SBA-15 amorphous molecular sieve and the template agent TPAOH can first pre-crystallize at a certain temperature and then crystallize at another temperature, introduce micropores in the case of retaining part of the mesopores in the pre-polymer SBA-15, and convert the amorphous molecular sieve into a zeolite molecular sieve, and the addition of the mineralizer NH4F can improve the crystallinity of the crystalline molecular sieve, thereby realizing one-step synthesis of a highly crystalline meso-microporous zeolite molecular sieve.

[0025] The application can realize efficient adsorption of volatile iodine without adding metals, the diameter of an iodine molecule is 0.26 nm, the pore of the solvent-free synthesized meso-microporous composite molecular sieve is 0.16 nm, the low pore can better adsorb gaseous iodine in the form of interaction force, and the introduction of mesopores can make the volatile iodine better flow in the pore channel of the adsorbent, thereby achieving the purpose of faster adsorption of gaseous iodine.

[0026] The application does not introduce metals, but only relies on the action of the pore, so the adsorption is physical adsorption, and there is no chemical adsorption behavior. Not only the cost is reduced, but also complete desorption can be achieved at 125 DEG C, so the application has better recycling property. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 N2 adsorption-desorption (left) and pore size distribution (right) of the meso-microporous composite zeolite molecular sieve;

[0028] Figure 2 Transmission electron microscopy (TEM) of the meso-microporous composite zeolite molecular sieve;

[0029] Figure 3 XRD patterns of the meso-microporous composite zeolite molecular sieve before and after iodine adsorption;

[0030] Figure 4 XRD patterns of the meso-microporous composite zeolite molecular sieve before and after iodine desorption. DETAILED DESCRIPTION

[0031] The application will be described in detail below in conjunction with the embodiments.

[0032] Embodiment 1:

[0033] The embodiment provides a preparation method of a meso-microporous zeolite molecular sieve for efficiently physically adsorbing gaseous iodine, comprising the following steps:

[0034] 1 g of PDMOS, 0.6 g of P123 and 0.03 g of PAG are added into a brown bottle, uniformly mixed and stirred to obtain a coating solution, the coating solution is uniformly applied on a substrate to form a liquid film, a full-wavelength high-pressure mercury lamp is used to irradiate the liquid film applied on the substrate to perform a photo reaction for 30 min, so that the PAG is decomposed, and a mesoporous molecular sieve film containing a template agent is obtained; 0.4 g of the mesoporous molecular sieve film containing the template agent, 0.2 g of TPAOH and 0.07 g of NH4F are put into a mortar and ground until a viscous substance is obtained, the viscous substance is put into a hydrothermal reaction kettle, crystallized at 80 ℃ for 2 days and then crystallized at 140 ℃ for 1 day, the obtained solid powder is washed and dried, and then put into a muffle furnace, heated to 550 ℃ at a heating rate of 1-5 ℃ / min, and calcined for 6 h to remove the template agent, so that a final product of the meso-microporous zeolite molecular sieve is obtained.

[0035] Embodiment 2:

[0036] The embodiment provides a preparation method of a meso-microporous zeolite molecular sieve for efficiently physically adsorbing gaseous iodine, comprising the following steps:

[0037] 1 g PDMOS, 0.6 g P123, 0.03 g PAG are added into a brown bottle, mixed and stirred uniformly to obtain a coating solution, the coating solution is uniformly applied on a substrate to form a liquid film, a full-wavelength high-pressure mercury lamp is used to irradiate the liquid film applied on the substrate to perform a photo reaction for 30 min, PAG is decomposed, and a mesoporous molecular sieve film containing a template agent is obtained; 0.4 g of the mesoporous molecular sieve film containing the template agent, 0.4 g of TPAOH and 0.07 g of NH4F are put into a mortar and ground until a viscous substance is obtained, the viscous substance is put into a hydrothermal reaction kettle, crystallized at 80 ℃ for 2 days, and then crystallized at 140 ℃ for 1 day, the obtained solid powder is washed and dried, and then put into a muffle furnace, heated to 550 ℃ at a heating rate of 1-5 ℃ / min, and calcined for 6 h to remove the template agent, and finally the product mesoporous-microporous zeolite molecular sieve is obtained.

[0038] Embodiment 3:

[0039] The embodiment provides a preparation method of a mesoporous-microporous zeolite molecular sieve for efficiently physically adsorbing gaseous iodine, which comprises the following steps:

[0040] 1 g PDMOS, 0.6 g P123, 0.03 g PAG are added into a brown bottle, mixed and stirred uniformly to obtain a coating solution, the coating solution is uniformly applied on a substrate to form a liquid film, a full-wavelength high-pressure mercury lamp is used to irradiate the liquid film applied on the substrate to perform a photo reaction for 30 min, PAG is decomposed, and a mesoporous molecular sieve film containing a template agent is obtained; 0.4 g of the mesoporous molecular sieve film containing the template agent, 0.8 g of TPAOH and 0.07 g of NH4F are put into a mortar and ground until a viscous substance is obtained, the viscous substance is put into a hydrothermal reaction kettle, crystallized at 80 ℃ for 2 days, and then crystallized at 140 ℃ for 1 day, the obtained solid powder is washed and dried, and then put into a muffle furnace, heated to 550 ℃ at a heating rate of 1-5 ℃ / min, and calcined for 6 h to remove the template agent, and finally the product mesoporous-microporous zeolite molecular sieve is obtained.

[0041] Embodiment 4:

[0042] The embodiment provides a preparation method of a mesoporous-microporous zeolite molecular sieve for efficiently physically adsorbing gaseous iodine, which comprises the following steps:

[0043] 1 g of PDMOS, 0.6 g of P123, and 0.03 g of PAG were added to a brown bottle and mixed thoroughly to obtain a coating solution. The coating solution was then evenly applied to a substrate to form a liquid film. The liquid film applied to the substrate was irradiated with a high-pressure mercury lamp of full wavelength for 30 min to induce a photoreaction, causing PAG to decompose and yield a mesoporous molecular sieve membrane containing a template agent. 0.4 g of the mesoporous molecular sieve membrane containing the template agent, 0.4 g of TPAOH, and 0.14 g of NH4F were then ground in a mortar until a viscous consistency was achieved. The viscous substance was placed in a hydrothermal reactor and crystallized at 80°C for 2 days, followed by crystallization at 140°C for 1 day. The resulting solid powder was washed, dried, and placed in a muffle furnace. The temperature was increased to 550°C at a rate of 1-5°C / min and calcined for 6 h to remove the template agent, yielding the final product, a mesoporous zeolite molecular sieve.

[0044] The performance parameters of the zeolites prepared in embodiments 1 to 4 above for adsorbing gaseous iodine are as follows:

[0045]

[0046] Performance Analysis: Implementation methods 1-3 discussed the effect of TPAOH amount on the catalyst pore structure. Experiments showed that the micropore size increased with increasing TPAOH amount. When TPAOH reached 0.8 g, the catalyst only exhibited a microporous structure. In the adsorption of volatile iodine, the saturation adsorption time of the fully microporous composite was greater than that of the mesoporous composite. However, when TPAOH was 0.4 g, the mesoporous pores in the mesoporous composite zeolite molecular sieve had an ordered structure, maximizing the adsorption of volatile iodine.

[0047] Methods 2 and 4 were used to discuss the effect of the amount of NH4F on the crystallinity of the mesoporous composite zeolite molecular sieve. The experimental results showed that the addition of the mineralizer NH4F could significantly improve the crystallinity, but the crystallinity decreased significantly with the increase of the water of crystallization in ammonium fluoride. The crystallinity of the mesoporous composite zeolite molecular sieve was better when the amount of NH4F was 0.07 g.

[0048] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a micro-mesoporous composite zeolite molecular sieve with high efficiency for physical adsorption of gaseous iodine, characterized in that, The method comprises the following steps: S1: adding a silicon source, a template agent P123 and a photoacid generator PAG into a brown bottle, mixing and stirring to obtain a coating solution; S2: uniformly applying the coating solution on a substrate to form a liquid film; S3: irradiating the liquid film applied on the substrate with a full-wavelength high-pressure mercury lamp for photo-reaction for 30 min to obtain a mesoporous molecular sieve film containing the template agent; S4: The mesoporous molecular sieve membrane, TPA + , NH4F were put into a mortar and ground until a viscous substance was obtained; S5: placing the viscous substance into a hydrothermal reactor, crystallizing at 70-100 ℃ for 1-3 days, and then crystallizing at 120-170 ℃ for 1-3 days, and then washing, drying to obtain a solid powder; S6: placing the solid powder into a muffle furnace to calcine and remove the template agent to obtain a meso-microporous composite zeolite molecular sieve.

2. The method for preparing the highly efficient physical adsorption gaseous iodine-enhancing mesoporous composite zeolite molecular sieve according to claim 1, characterized in that: In S4, the mass ratio of the mesoporous molecular sieve membrane, TPA + NH4F is 1:0.5-2:0.2-1.

3. The method for preparing the highly efficient physical adsorption gaseous iodine-enhancing mesoporous composite zeolite molecular sieve according to claim 2, characterized in that: The TPA + is TPAOH in an amount of 10% to 50%.

4. The method of claim 1, wherein the method is characterized by: In S4, the water content of the viscous substance is 1%-5%.

5. The method of claim 1, wherein the method is characterized by: In S1, the mass ratio of the silicon source, the template agent P123 and the photoacid generator PAG is 1:0.6:0.

03.

6. The method for preparing the highly efficient physical adsorption gaseous iodine-enhancing mesoporous composite zeolite molecular sieve according to claim 5, characterized in that: The silicon source is PDMOS.

7. The method of claim 5, wherein the method further comprises: (a) mixing the mixture of step (b) with a zeolite seed crystal; and (b) heating the mixture of step (a) to a temperature of 100°C to 200°C for 1 to 10 hours. The photoacid generator PAG is diphenyl iodonium hexafluorophosphate.

8. The method for preparing the highly efficient physical adsorption gaseous iodine-enhancing mesoporous composite zeolite molecular sieve according to claim 1, characterized in that: In S6, the specific conditions of the calcination are as follows: Rising the temperature to 450-600 ℃ at a temperature rising rate of 1-5 ℃ / min, and calcining for 5-8 h.

9. Application of a meso-microporous composite zeolite molecular sieve prepared by the method of any one of claims 1-8 in physical adsorption of gaseous iodine.

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