Zeolite structure single crystal as well as preparation method and application thereof

Abstract

The invention discloses a preparation method and application of a zeolite structure single crystal, and belongs to the technical field of zeolite structure crystal preparation. The preparation method disclosed by the invention comprises the following steps: mixing oxide powder and CsCl-CsF eutectic salt, and carrying out heat treatment in an inert atmosphere to obtain a product; and carrying out post-treatment on the product to obtain the zeolite structure single crystal. And the oxide powder is SiO2 powder or GeO2 powder. According to the method disclosed by the invention, the zeolite structure single crystal is prepared by a new way of a'one-pot method ', the growth process is simple, the equipment is simple, the cost is relatively low, and the technical problem that large-scale production is difficult to realize due to complicated steps, high equipment requirements and the like of a traditional preparation method is simply and effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of zeolite structure crystal preparation technology, specifically relating to a method for preparing zeolite structure single crystals and their applications. Background Art

[0002] Traditional aluminosilicate zeolite is composed of corner-shared tetrahedrons. T O4 unit ( T Zeolite materials are composed of elements such as Si and Al, forming a microporous structure with periodic one- to three-dimensional channels. The unique pore structure, large specific surface area, molecular-level shape selectivity, tunable active sites, and excellent thermal stability exhibited by characteristic zeolite structures make them important in energy, chemical production, heterogeneous catalysis, and adsorption separation.

[0003] Controlling the concentration and distribution of aluminum atoms in the traditional aluminosilicate zeolite framework directly affects the hydrophilicity / hydrophobicity and stability of the zeolite, thereby enabling functional applications. Adjusting the Si / Al ratio to achieve aluminum-rich CHA zeolite (Si / Al ~1) enables the adsorption and separation of CO2 / CH4, selectively capturing CH4. Some high-silica zeolites, such as ZSM-5 (Si / Al=80) and MOR (Si / Al=200), exhibit highly efficient removal capabilities for nitrosamines in demineralized water. In particular, fully dealuminized pure silica zeolites have achieved new breakthroughs in the application of traditional aluminosilicate zeolites. For example, MFI, *BEA, and MEL zeolites are used as ultra-low dielectric constant materials in integrated circuits, providing new material options for solving the bottleneck problems in the development of next-generation chips in the semiconductor industry. Similarly, the large total surface area and pore volume, as well as excellent hydrophobicity, of pure silica zeolite endow it with stable and reusable performance in effectively adsorbing volatile organic compounds.

[0004] Currently, the hydrothermal method is commonly used to prepare aluminosilicate zeolites and pure silicon / germanium zeolites. The general strategy involves synthesizing host and guest compounds using suitable (usually organic) structure-directing agents (also known as template agents), followed by the removal of the guest organic matter. In this method, the structure-directing agent provides the necessary kinetic pathway and additional stabilizing energy. Based on this, researchers have conducted numerous optimizations and modifications, such as the fluorine-free or seedless synthesis of high-silica *BEA zeolites, single-step or multi-step acid etching of previously synthesized zeolite frameworks, top-down surface modification processes (σ-expansion), and amine chemical attack to break down -Si-O-Si- bonds in the framework, resulting in larger pores. However, this preparation strategy also has significant limitations. For example, the reaction conditions are stringent, and the appropriate organic amines and solution alkalinity affect channel stability and nucleation / crystallization rates, easily leading to framework collapse and affecting product quality. Furthermore, the complex synthesis steps waste a large amount of chemical raw materials, limiting subsequent industrialization. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing zeolite structured single crystals and its application, in order to solve the technical problems that traditional preparation methods have many complex steps and demanding reaction conditions, making it difficult to achieve large-scale production.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing zeolite structured single crystals, comprising the following steps: The oxide powder and CsCl-CsF eutectic salt were mixed and then heat-treated in an inert atmosphere to obtain the product; the product was then post-treated to obtain a zeolite structure single crystal. The oxide powder is SiO2 powder or GeO2 powder.

[0007] Furthermore, the preparation method of the CsCl-CsF eutectic salt is as follows: CsCl and CsF are mixed and ground to obtain the CsCl-CsF eutectic salt; In the CsCl-CsF eutectic salt, the molar percentage of CsF is 35%~60%.

[0008] Furthermore, the mass ratio of the CsCl-CsF eutectic salt to the oxide powder is (10~50):1.

[0009] Furthermore, after mixing the oxide powder and CsCl-CsF eutectic salt, the mixture is placed in an Ag crucible, and then the Ag crucible is placed in a ceramic crucible for heat treatment in an argon atmosphere. The ceramic crucible is of the type Al2O3 crucible, quartz crucible, zirconium oxide crucible or silicon carbide crucible.

[0010] Furthermore, the heat treatment temperature is 800~950 ℃, the time is 12~30 h, and the heating rate of the heat treatment is 200~400 ℃ / h.

[0011] Furthermore, the heat treatment temperature is 850~900 ℃, and the time is 20~28 h.

[0012] Furthermore, the post-processing includes a cooling process and a cleaning process performed sequentially; The cooling process is as follows: the temperature is reduced to 300-650 ℃ at a rate of 2-8 ℃ / h, then the temperature control is stopped and the temperature is allowed to cool naturally to room temperature.

[0013] Furthermore, the cooling process is as follows: the temperature is reduced to 400-500 ℃ at a rate of 2-8 ℃ / h, then the temperature control is stopped, and the temperature is allowed to cool naturally to room temperature.

[0014] This invention also discloses a zeolite-structured single crystal prepared by the above-described method, wherein the chemical formula of the zeolite-structured single crystal is: Cs T 2.75 O6, of which T The compounds are Si and Ge; where CsSi 2.75 The O6 single-crystal structure is a pure silica zeolite structure with an acridite-type structure, CsGe 2.75 The O6 single crystal structure is a pure germanium zeolite structure with cesium garnet type; the size of the zeolite structure single crystal is (0.05~0.30)mm×(0.05~0.30)mm×(0.01~0.05)mm.

[0015] This invention also discloses the applications of the above-mentioned zeolite structure single crystals, including their application in the selective capture and effective adsorption separation of organic pollutants, and their application in the immobilization and sequestration of Cs elements in the disposal of high-level radioactive waste.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing zeolite-structured single crystals. The method uses CsCl-CsF eutectic salt as a flux to heat-melt SiO2 or GeO2 powder in an inert atmosphere. The product is then post-treated to achieve supersaturation in the molten state, driving crystal growth to ultimately obtain zeolite-structured single crystals. This method uses a novel "one-pot" approach to prepare zeolite-structured single crystals. The growth process is simple, the equipment is basic, and the cost is low. It effectively solves the technical problem of traditional preparation methods being complex and requiring high-end equipment, making large-scale production difficult.

[0017] Furthermore, this method uses CsCl-CsF eutectic salt as a flux, which will not chemically react with the generated zeolite structure single crystal, thus facilitating the acquisition of new crystal products with pure silicon and pure germanium zeolite structures.

[0018] Furthermore, the post-processing of this method employs a slow cooling rate, which drives crystal growth. At the same time, the temperature control cooling is preferably set at 400~500 ℃, which is beneficial for preparing high-quality zeolite structure single crystals.

[0019] This invention also discloses zeolite-structured single-crystal Cs prepared by the above-described preparation method. T 2.75 O6( T =Si,Ge), where CsSi 2.75 The O6 single-crystal structure is a pure silica zeolite structure with an acridite-type structure, CsGe 2.75The O6 single-crystal structure is a pure germanium zeolite structure with cesium garnet type. In subsequent applications of pure silicon zeolite, it is expected to achieve higher performance and more groundbreaking adsorption separation and catalytic applications by gradually controlling the concentration and distribution of Al atoms in the pure silicon framework, thereby broadening the application prospects of pure silicon and pure germanium zeolites with more diverse framework structures. Attached Figure Description

[0020] Figure 1 The sheet-like CsSi prepared in Example 1 of this invention 2.75 O6 single crystal and bulk CsGe 2.75 O6 single crystal micrograph; Wherein: (1-1): CsSi 2.75 O6 single crystal products; (1-2): CsGe 2.75 O6 single crystal product; Figure 2 The sheet-like CsSi prepared in Example 1 of this invention 2.75 O6 single crystal and CsGe 2.75 Comparison of powder diffraction patterns of O6 single crystals with theoretical data; Wherein: (2-1): CsSi 2.75 O6 single crystal; (2-2): Bulk CsGe 2.75 O6 single crystal; Figure 3 The sheet-like CsSi prepared in Example 1 of this invention 2.75 O6 single crystal and bulk CsGe 2.75 SEM-EDS spot analysis pattern of O6 single crystal; Wherein: (3-1): CsSi 2.75 O6 single crystal; (3-2): Bulk CsGe 2.75 O6 single crystal; Figure 4 This is a stereomicroscope image of the product prepared using GeO2 powder as a raw material in Example 2. Figure 5 These are stereomicroscope images of the products prepared using SiO2 and GeO2 powders as raw materials, respectively, in Example 4. Figure 6 These are stereomicroscope images of the products prepared using SiO2 and GeO2 powders as raw materials, respectively, in Example 8. Figure 7 These are stereomicroscope images of the products prepared using SiO2 and GeO2 powders as raw materials in Example 10. Figure 8 The images shown are stereomicroscopic images of the products prepared using SiO2 and GeO2 powders as raw materials, respectively, as shown in Example 12. Detailed Implementation

[0021] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0022] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0023] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0024] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0025] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0026] This invention provides a method for preparing zeolite-structured single crystals, and a method for growing Cs using a halide flux and SiO2 or GeO2 as raw materials. T 2.75 O6( T A new approach to obtaining high-quality new single crystals of CsSi (Si,Ge) yields colorless, plate-like acrid zeolite-type CsSi capable of single-crystal X-ray diffraction. 2.75 New O6 crystals and massive cesium garnet-type CsGe 2.75 The new O6 crystal enriches the structural types of pure silicon / germanium zeolites and provides new ideas for the subsequent exploration and development of applications of pure silicon / germanium zeolite materials. The main steps include: Step 1: Load SiO2 or GeO2 powder and CsCl-CsF eutectic salt into an Ag crucible; Step 2: The Ag crucible is then placed in a ceramic crucible and heat-treated in a glove box filled with argon atmosphere to obtain the product; the product is cooled to room temperature and then cleaned to obtain a zeolite structure single crystal.

[0027] Preferably, in step 1, the CsCl-CsF eutectic salt is formed by mixing and grinding CsCl and CsF; in the CsCl-CsF eutectic salt, the molar percentage of CsF is 35%~60%; more preferably, the molar percentage of CsF is 40%~55%.

[0028] Preferably, in step 1, the mass ratio of CsCl-CsF eutectic salt to SiO2 or GeO2 powder is (10~50):1; more preferably, the mass ratio of CsCl-CsF eutectic salt to SiO2 or GeO2 powder is (20~30):1.

[0029] Preferably, in step 2, the heat treatment temperature is 800~950 ℃, more preferably 850~900 ℃, and the heat treatment time is 12~30 h, even more preferably 20~28 h.

[0030] Preferably, in step 2, the heat treatment is carried out by heating to the heat treatment temperature at a rate of 200~400 ℃ / h.

[0031] Preferably, in step 2, the cooling process includes: cooling to 300-650 ℃ at a rate of 2-8 ℃ / h, then stopping temperature control and allowing it to cool naturally to room temperature; more preferably, in step 2, the cooling process includes: cooling to 400-500 ℃ at a rate of 2-8 ℃ / h, then stopping temperature control and allowing it to cool naturally to room temperature; stopping the programmed temperature control setting when cooling to 400-500 ℃ at a slow cooling rate, followed by natural cooling, is beneficial for preparing higher quality zeolite structure single crystal products.

[0032] The preparation method of this invention uses CsCl-CsF eutectic salt as a flux, which has a low eutectic point. SiO2 or GeO2 powder and CsCl-CsF eutectic salt are mixed and heat-treated at high temperature. The SiO2 or GeO2 powder begins to melt at the eutectic point of the flux CsCl-CsF (approximately 450°C), and the temperature is raised to 900°C to obtain a homogeneous molten state. Finally, a slow cooling process is used to allow the molten state of the reacted products to reach supersaturation, driving crystal growth to obtain CsCl-CsF. T 2.75 O6( T A new single-crystal product (Si, Ge) was obtained. This method uses a one-pot preparation process, which is simpler in growth process, requires simpler equipment, and has lower cost compared to the previous hydrothermal method for zeolite preparation, thus facilitating subsequent industrial development.

[0033] This invention also discloses a zeolite-structured single crystal prepared by the above-described method, wherein the chemical formula of the zeolite-structured single crystal is Cs. T 2.75 O6( T =Si,Ge); the size of the zeolite structure single crystal is (0.05~0.30) mm×(0.05~0.30) mm×(0.01~0.05) mm, and the crystal morphology is colorless and transparent plate-like or block-like single crystal.

[0034] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0035] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0036] Example 1 The preparation method of zeolite structured single crystals includes the following steps: Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, colorless and transparent flake-like CsSi was obtained. 2.75O6 single crystal and bulk CsGe 2.75 O6 single crystal.

[0037] The colorless and transparent sheet-like CsSi obtained in this embodiment 2.75 O6 single crystal and bulk CsGe 2.75 See the stereomicroscope image of the O6 single crystal. Figure 1 As shown. Colorless and transparent sheet-like CsSi 2.75 O6 single crystal and bulk CsGe 2.75 Comparison of powder diffraction patterns and theoretical data for O6 single crystals, for example... Figure 2 As shown in the figure, the invention prepares Cs T 2.75 O6( T =Si,Ge) zeolite structure, a new single-crystal phase, is difficult to obtain single-phase CsSi through reaction. 2.75 O6 products are usually formed along with other impurity phases, and the CsGe obtained from the reaction 2.75 The diffraction peak positions of the O6 product basically match the theoretical peak values ​​and there are no obvious impurity peaks.

[0038] Further analysis of the obtained colorless and transparent sheet-like CsSi 2.75 O6 single crystal and bulk CsGe 2.75 O6 single crystal was subjected to SEM-EDS spot scanning, such as Figure 3 As shown, the two types of products contain only Cs,Si,O and Cs,Ge,O elements, respectively. Although the EDS results are mainly used for qualitative analysis, it can be seen that the energy dispersive spectroscopy results of these two types of crystals roughly conform to the atomic ratio of the chemical formula.

[0039] Comparative Example 2 Step 1: In an atmospheric environment, weigh 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were: the mixture was heated from 25 ℃ to 900 ℃ at a heating rate of 300 ℃ / h, and held at 900 ℃ for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 ℃ at a cooling rate of 3 ℃ / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, no obvious product was obtained using SiO2 powder as raw material, and an unidentifiable white amorphous powder product was obtained using GeO2 powder as raw material. See the stereomicroscopic crystal image. Figure 4 .

[0040] A comparison of Examples 1 and 2 shows that it is difficult to obtain CsSi with an anticline-type pure silica zeolite structure in an atmospheric environment. 2.75 O6 single crystal products and CsGe with cesium garnet-type pure silica zeolite structure 2.75 O6 single crystal product.

[0041] Example 3 Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 1.2g and 1.0g of CsCl-CsF eutectic salt respectively, and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1 respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place the two Ag crucibles into the two Al2O3 crucibles respectively, followed by heat treatment. The heat treatment process parameters were: the mixture was heated from 25 ℃ to 900 ℃ at a heating rate of 300 ℃ / h, and the temperature was maintained at 900 ℃ for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 ℃ at a cooling rate of 3 ℃ / h, and the temperature control program was stopped. The mixture was allowed to cool naturally to room temperature. After further cleaning, no obvious product was obtained using SiO2 powder as raw material, while a blocky CsGe containing a large amount of white unknown powder was obtained using GeO2 powder as raw material. 2.75 O6 single crystal.

[0042] Example 4 Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 1.8g and 1.6g of CsCl-CsF eutectic salt respectively, and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1 respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, smaller CsSi containing other unknown phases was obtained using SiO2 powder as the raw material. 2.75 O6 single crystal, using GeO2 powder as raw material to obtain bulk CsGe containing a large number of tiny crystal grains 2.75 O6 single crystal, its stereomicroscope crystal photograph is shown below Figure 5 .

[0043] Example 5 Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 2.4g and 2.1g of CsCl-CsF eutectic salt respectively, and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1 respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, smaller CsSi particles were obtained using SiO2 powder as the raw material. 2.75 O6 single crystal, using GeO2 powder as raw material to obtain bulk CsGe containing a large number of tiny crystal grains 2.75 O6 single crystal.

[0044] Comparing Examples 1, 3, 4, and 5, it can be seen that the mass ratio of the eutectic salt to the raw material directly affects the solubility and distribution uniformity of the raw material in the molten salt. CsSi can be prepared by using a mass ratio of CsCl-CsF eutectic salt to SiO2 or GeO2 powder of 15:1, 20:1, and 30:1. 2.75 O6 single crystal and CsGe 2.75 O6 single crystals, however, relatively speaking, controlling the mass ratio of eutectic salt to raw materials at 30:1 can better prepare CsSi with no obvious impurity phases and higher crystal quality. 2.75 O6 single crystal products and CsGe 2.75 O6 single crystal product.

[0045] Example 6 The preparation method of zeolite structured single crystals includes the following steps: Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 50%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, colorless and transparent flake-like CsSi was obtained. 2.75 O6 single crystal and bulk CsGe 2.75 O6 single crystal.

[0046] Example 7 The preparation method of zeolite structured single crystals includes the following steps: Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 55%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, colorless and transparent flake-like CsSi was obtained. 2.75 O6 single crystal and bulk CsGe 2.75 O6 single crystal.

[0047] By comparing Examples 1, 6, and 7, it can be seen that changing the ratio of CsCl and CsF in the eutectic salt flux, with the molar ratio of CsF being 45%, 50%, and 55%, respectively, yields CsSi... 2.75 O6 single crystal and CsGe 2.75 There was no significant difference in the single-crystal products of O6.

[0048] Example 8 Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 ℃ to 800 ℃ at a heating rate of 300 ℃ / h, and held at 800 ℃ for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 ℃ at a cooling rate of 3 ℃ / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, bulk CsSi with poor crystal quality was obtained using SiO2 powder as raw material. 2.75 O6 single crystal, and bulk CsGeO2 containing a large number of other unknown phases as the main phase obtained from GeO2 powder.2.75 O6 single crystal, its stereomicroscope crystal photograph is shown below Figure 6 .

[0049] Example 9 The preparation method of zeolite structured single crystals includes the following steps: Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 ℃ to 850 ℃ at a heating rate of 850 ℃ / h, and held at 850 ℃ for 24 h. After the reaction, the product was obtained. The product was then cooled to 400 ℃ at a cooling rate of 3 ℃ / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, colorless and transparent CsSi was obtained. 2.75 O6 single crystal and CsGe 2.75 The O6 single crystal product showed no significant difference in quality compared to the product in Example 1.

[0050] Comparing Examples 1, 8, and 9, it can be seen that lowering the high-temperature treatment temperature to 800 °C may affect the solubility of the raw material in the molten salt, leading to a decrease in supersaturation and thus affecting the crystal quality. Simultaneously, lowering the temperature may also alter the reaction kinetics, causing changes in the reaction pathway and resulting in different product phases, ultimately yielding CsSi with inferior quality. 2.75 O6 single crystal and CsGe-containing 2.75 The multiphase product of O6 single crystal, while CsSi prepared at temperatures of 850 ℃ and 900 ℃ 2.75 O6 single crystal and CsGe 2.75 The quality of O6 single crystal products is relatively stable with no significant difference.

[0051] Example 10 Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters are as follows: heat the mixture from 25 ℃ to 900 ℃ at a heating rate of 300 ℃ / h, maintain the temperature at 900 ℃ for 12 h, and obtain the product. Then, cool the product to 400 ℃ at a cooling rate of 3 ℃ / h, stop the programmed temperature control, and allow it to cool naturally to room temperature. After further cleaning, blocky CsSi with generally small crystal size is obtained using SiO2 powder as the raw material. 2.75 Due to incomplete cleaning, the O6 single crystal inevitably retained some unknown gel-like impurities. Using GeO2 powder as raw material, a large number of other poor-quality columnar unknown crystals and large, poor-quality CsGe were obtained. 2.75 O6 crystal, its stereomicroscopic crystal photograph is shown in... Figure 7 .

[0052] Example 11 The preparation method of zeolite structured single crystals includes the following steps: Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 28 h. After the reaction, the product was obtained. The product was then cooled to 400 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, colorless and transparent CsSi was obtained. 2.75 O6 single crystal and CsGe2.75 The O6 single crystal product showed no significant difference in quality compared to the product in Example 1.

[0053] Comparing Examples 1, 10, and 11, it can be seen that reducing the high-temperature treatment time to 12 hours may affect the uniform distribution and full reaction of the raw materials in the molten salt. This may result in the formation of some difficult-to-clean, unknown gel-like impurities in the product obtained using SiO2 powder as a raw material, limiting the formation of the target product. Therefore, increasing the high-temperature treatment time is beneficial for obtaining high-quality CsSi. 2.75 O6 single crystal and CsGe 2.75 O6 single crystal product.

[0054] Example 12 Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place the two Ag crucibles into the two Al2O3 crucibles respectively, followed by heat treatment. The heat treatment process parameters are as follows: the mixture is heated from 25 ℃ to 900 ℃ at a heating rate of 300 ℃ / h, and the temperature is maintained at 900 ℃ for 24 h. After the reaction, the product is obtained. The product is then cooled to 600 ℃ at a cooling rate of 3 ℃ / h, and the programmed temperature control is stopped. It is then allowed to cool naturally to room temperature. After further cleaning, a colorless and transparent spherical unknown single crystal is obtained from SiO2 powder, and a blocky CsGe containing other unknown phases with poor crystal quality is obtained from GeO2 powder. 2.75 O6 crystal products, and their stereomicroscopic crystal photographs are shown below. Figure 8 .

[0055] Example 13 The preparation method of zeolite structured single crystals includes the following steps: Step 1: In a glove box filled with argon atmosphere, weigh out 0.1202g of SiO2 powder and 0.1046g of GeO2 powder and place them into two Ag crucibles respectively; Step 2: Weigh 3.1g of CsCl-CsF eutectic salt and place them into the two Ag crucibles that were filled with SiO2 powder and GeO2 powder in Step 1, respectively; The preparation method of CsCl-CsF eutectic salt is as follows: weigh CsCl and CsF such that the molar ratio of CsF is 45%, put them into a mortar and grind them. After grinding, CsCl-CsF eutectic salt is obtained. Step 3: Cover the two Ag crucibles with silver lids, then place each Ag crucible into a separate Al2O3 crucible, followed by heat treatment. The heat treatment parameters were as follows: the mixture was heated from 25 °C to 900 °C at a heating rate of 300 °C / h, and held at 900 °C for 24 h. After the reaction, the product was obtained. The product was then cooled to 450 °C at a cooling rate of 3 °C / h, at which point the programmed temperature control was stopped, and the mixture was allowed to cool naturally to room temperature. After further cleaning, colorless and transparent CsSi was obtained. 2.75 O6 single crystal and CsGe 2.75 The O6 single crystal product showed no significant difference in quality compared to the product in Example 1.

[0056] Comparing Examples 1, 12, and 13, it can be seen that excessively high temperatures after the high-temperature treatment and subsequent slow cooling may lead to incomplete crystal growth, increased structural defects, or the formation of impurity phases. Temperatures of 400 °C and 450 °C are more suitable, which is beneficial for obtaining CsSi with stable structure, fewer defects, and higher quality. 2.75 O6 single crystal and CsGe 2.75 O6 single crystal product.

[0057] The method of this invention uses SiO2 or GeO2 as raw material, combined with CsCl-CsF eutectic salt flux, and reacts in an Ag crucible under an inert argon atmosphere to prepare pure silicon and pure germanium zeolite-structured Cs using a novel "one-pot" method. T 2.75 O6( T The new single crystal of Si,Ge has solved the problem of the traditional hydrothermal method being complex and requiring high-end equipment, making it difficult to achieve industrial-scale growth.

[0058] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing zeolite-structured single crystals, characterized in that, Includes the following steps: The oxide powder and CsCl-CsF eutectic salt were mixed and then heat-treated in an inert atmosphere to obtain the product; the product was then post-treated to obtain a zeolite structure single crystal. The oxide powder is SiO2 powder or GeO2 powder.

2. The method for preparing a zeolite-structured single crystal according to claim 1, characterized in that, The preparation method of the CsCl-CsF eutectic salt is as follows: CsCl and CsF are mixed and ground to obtain the CsCl-CsF eutectic salt; In the CsCl-CsF eutectic salt, the molar percentage of CsF is 35%~60%.

3. The method for preparing a zeolite-structured single crystal according to claim 1, characterized in that, The mass ratio of the CsCl-CsF eutectic salt to the oxide powder is (10~50):

1.

4. The method for preparing a zeolite-structured single crystal according to claim 1, characterized in that, The oxide powder and CsCl-CsF eutectic salt are mixed and placed in an Ag crucible. The Ag crucible is then placed in a ceramic crucible and heat-treated in an argon atmosphere. The ceramic crucible is of the type Al2O3 crucible, quartz crucible, zirconium oxide crucible or silicon carbide crucible.

5. The method for preparing a zeolite-structured single crystal according to claim 1, characterized in that, The heat treatment temperature is 800~950 ℃, and the time is 12~30 h; the heating rate of the heat treatment is 200~400 ℃ / h.

6. The method for preparing a zeolite-structured single crystal according to claim 1, characterized in that, The heat treatment is performed at a temperature of 850~900 ℃ for a time of 20~28 h.

7. The method for preparing a zeolite-structured single crystal according to claim 1, characterized in that, The post-processing includes sequential cooling and cleaning processes; The cooling process is as follows: the temperature is reduced to 300-650 ℃ at a rate of 2-8 ℃ / h, then the temperature control is stopped and the temperature is allowed to cool naturally to room temperature.

8. A method for preparing a zeolite-structured single crystal according to claim 7, characterized in that, The cooling process is as follows: the temperature is reduced to 400-500 ℃ at a rate of 2-8 ℃ / h, then the temperature control is stopped and the temperature is allowed to cool naturally to room temperature.

9. A zeolite-structured single crystal, characterized in that, The zeolite single crystal was prepared by the preparation method according to any one of claims 1 to 8, and the chemical formula of the zeolite single crystal is: Cs T 2.75 O6, of which T For Si and Ge; Among them, CsSi 2.75 The O6 single-crystal structure is a pure silica zeolite structure with an acridite-type structure, CsGe 2.75 The O6 single crystal structure is a pure germanium zeolite structure with cesium garnet type; the size of the zeolite structure single crystal is (0.05~0.30)mm×(0.05~0.30)mm×(0.01~0.05)mm.

10. The application of the zeolite structure single crystal according to claim 9, characterized in that, Applications of the zeolite-structured single crystals in the selective capture and effective adsorption separation of organic pollutants; applications of the zeolite-structured single crystals in the fixation and sequestration of Cs elements in the disposal of high-level radioactive waste.

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