A sheet-like EU-1 molecular sieve, its preparation method and application

Abstract

This invention provides a sheet-like EU-1 molecular sieve, its preparation method, and its applications. The EU-1 molecular sieve of this invention has a thin sheet-like structure with a sheet thickness of 20-50 nm, exhibiting a high silicon-to-aluminum ratio, large specific surface area, and high stability. The method for synthesizing the sheet-like EU-1 molecular sieve of this invention is a one-step synthesis process, which is simple to operate, highly efficient, produces high-purity and reproducible products, requires no organic base, and is low-cost.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve technology, specifically to a sheet-like EU-1 molecular sieve, its preparation method, and its application. Background Technology

[0002] EU-1 molecular sieves were first synthesized by Casci in the 1980s using hexamethyl diammonium cations as template agents. They possess a one-dimensional ten-membered ring channel structure (0.58 × 0.41 nm) and twelve-membered ring side pockets (0.68 × 0.58 nm), belonging to the orthorhombic crystal system with space group Cmma. EU-1 molecular sieves exhibit unique channel structures and demonstrate excellent catalytic performance in reactions such as aromatic hydrocarbon conversion, methanol-to-propylene (MTP), and naphtha cracking. For example, in the xylene isomerization reaction, EU-1 molecular sieves exhibit superior activity and selectivity, outperforming industrially used mordenite (MOR) and ZSM-5 molecular sieves in terms of total C8 aromatic hydrocarbon loss, as well as disproportionation and alkyl transfer losses. Therefore, the synthesis of EU-1 molecular sieves is of great significance in both theoretical research and practical applications.

[0003] In existing technologies, hexamethylammonium bromide is commonly used as a template agent to synthesize EU-1 molecular sieves via a hydrothermal method. This method can synthesize pure-phase EU-1 molecular sieves when the silicon-to-aluminum ratio is below 120. However, when the silicon-to-aluminum ratio is high, the surface activation energy for nucleation and crystallization of EU-1 molecular sieves is higher than that for ZSM-48 molecular sieves. The synthesized EU-1 molecular sieves are in a metastable state and are easily transformed into ZSM-48 molecular sieves, making it difficult to synthesize pure-phase EU-1 molecular sieves.

[0004] Therefore, people have improved the above methods by introducing seed crystals or using organic bases or composite templates to obtain pure-phase EU-1 molecular sieves or increase the silica-alumina ratio of EU-1 molecular sieves. For example, Xu et al. (Xu QH, Journal of Colloid and Interface Science, 2011, 358(1):252-260) effectively reduced the nucleation activation energy of high-silicon EU-1 molecular sieves by adding seed crystals to the system, thereby inhibiting the formation of ZSM-48 and preparing pure-phase high silica-alumina ratio EU-1 molecular sieves. However, this method requires the separate preparation of seed crystals and cannot synthesize high-silicon EU-1 molecular sieves in one step, making the entire preparation process relatively complex. LI et al. (LI XF, Journal of Porous Materials, 2016, 23(6):1557-1565) successfully increased the silica-alumina ratio of EU-1 molecular sieves using the organic base source tetraethylammonium hydroxide (TEAOH). They believed that TEA +This method better matches the lower negative charge density in the framework of high-silica EU-1 molecular sieves, but its high cost stems from the use of the organic base TEAOH as the alkali source. CN103301877A discloses a method for synthesizing high-silica EU-1 in a microemulsion system formed by a non-water-soluble organic solvent, using hexamethyldiammonium and dibenzyldimethylammonium as composite template agents, adding EU-1 seed crystals, and using inorganic salts and surfactants as co-promoters. This method requires seed crystal preparation or a two-stage crystallization method, making the preparation of EU-1 molecular sieves relatively complex. CN1259399A discloses a method for preparing EU-1 molecular sieves, which uses a template agent precursor to synthesize zeolite. Seed crystals can be added during synthesis to shorten the crystallization time, but the synthesis time is long (over 100 hours) and the yield is low (below 5%). The prepared EU-1 molecular sieve has a low silica-alumina ratio, with a maximum of 200.

[0005] In addition, EU-1 molecular sieves in the prior art are usually oval-shaped, and there are no reports of plate-shaped EU-1 molecular sieves. Summary of the Invention

[0006] To address one of the aforementioned technical problems in the prior art, this invention provides a sheet-like EU-1 molecular sieve and its preparation method. The EU-1 molecular sieve of this invention has a sheet-like structure and a high silica-to-alumina ratio. Compared to EU-1 molecular sieves with non-sheet-like morphologies (e.g., olive-shaped, rod-shaped, granular, etc.) in the prior art, it has a larger specific surface area and higher hydrothermal stability, resulting in better catalytic performance. The preparation process of this invention does not require the addition of seed crystals or other additives, nor does it require the use of organic bases. A pure-phase EU-1 molecular sieve with a high silica-to-alumina ratio can be prepared in one step. The process is simple, low-cost, has a short crystallization time, and produces a product with high crystallinity. It can efficiently and stably synthesize EU-1 molecular sieves with a high silica-to-alumina ratio, making it suitable for industrial production.

[0007] In a first aspect, the present invention provides a sheet-like EU-1 molecular sieve with a sheet thickness of 20-50 nm.

[0008] The EU-1 molecular sieve of the present invention is in the form of thin sheets and has a morphology completely different from that of the EU-1 molecular sieves in the prior art. By improving the morphology and structure of the EU-1 molecular sieve, its performance in catalysis, adsorption and other aspects can be further improved.

[0009] It should be noted that the sheet thickness described in this invention is the average thickness of the sheet.

[0010] In some embodiments, the specific surface area of ​​the molecular sieve is greater than 200 m². 2 ·g -1 .

[0011] In some embodiments, the silica-alumina molar ratio (SiO2 / Al2O3) of the molecular sieve is 350-700. The EU-1 molecular sieve of the present invention has a high silica-alumina molar ratio. Based on previous studies of molecular sieves, high silica-alumina ratio molecular sieves exhibit weaker acidity and stronger thermal and hydrothermal stability. The high silica-alumina ratio EU-1 molecular sieve demonstrates higher propylene selectivity in the MTP reaction and can significantly reduce C2. 5+ The yield of hydrocarbons, while maintaining a high product P / E ratio.

[0012] In a second aspect, the present invention provides a method for preparing the sheet-like EU-1 molecular sieve described in the first aspect, comprising the following steps:

[0013] A mixture containing an inorganic alkali source, an aluminum source, a template agent, a silicon source, and water is crystallized to obtain a sheet-like EU-1 molecular sieve; wherein, in the mixture, the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of SiO2 to Al2O3 is 1:(0.001-0.003).

[0014] The method of this invention, using a specific ratio of SiO2 to Al2O3, successfully synthesized sheet-like EU-1 molecular sieves without adding seed crystals, which differs from the morphology of existing EU-1 molecular sieves (rugby ball shape, granular shape, etc.). Furthermore, the preparation method of this invention does not use organic bases, resulting in low cost.

[0015] In this invention, there are no special requirements for the preparation method of the mixture. In some embodiments, the preparation method of the mixture includes: sequentially adding an inorganic alkali source, an aluminum source, a template agent, and a silicon source to water, stirring, and obtaining a gel mixture.

[0016] In the mixture described in this invention, the molar ratio of SiO2 to Al2O3 is 1:(0.001-0.003), for example, it can be 1:0.001, 1:0.0012, 1:0.0015, 1:0.0018, 1:0.002, 1:0.0022, 1:0.0025, 1:0.0028, 1:0.003 or any value between them, preferably 1:(0.0012-0.0025). This invention can obtain sheet-like EU-1 molecular sieves with different SiO2 / Al2O3 molar ratios by adjusting the ratio of silicon source to aluminum source in the mixture, and can control the SiO2 / Al2O3 molar ratio of the sheet-like EU-1 molecular sieve within the range of 350-700, achieving a one-step rapid and efficient preparation of EU-1 molecular sieves with a high SiO2 / Al2O3 molar ratio.

[0017] In some embodiments, the inorganic alkali source is at least one selected from alkali metal oxides, alkali metal hydroxides, and alkali metal carbonates. In some embodiments, the inorganic alkali source is an alkali metal hydroxide. In some embodiments, the inorganic alkali source is at least one selected from lithium hydroxide, sodium hydroxide, and potassium hydroxide.

[0018] In some embodiments, the silicon source is selected from one or more of silica sol, water glass, and silicate esters.

[0019] In some embodiments, the aluminum source is selected from one or more of sodium aluminate, aluminum nitrate nonahydrate, boehmite, and aluminum isopropoxide.

[0020] The template agent in this invention can be a single template agent, hexamethylammonium bromide, to synthesize plate-like EU-1 molecular sieves with a high silicon-to-aluminum ratio. Alternatively, other template agents such as benzyldimethylamine, tetramethylammonium bromide, tetraethylammonium bromide, and tetrapropylammonium bromide can be combined with hexamethylammonium bromide. The two can synergistically act as structure directing agents, template fillers, or balance framework charges, thereby enabling the synthesis of plate-like EU-1 molecular sieves with a high silicon-to-aluminum molar ratio.

[0021] In some embodiments, the template agent comprises hexamethylammonium bromide. In some embodiments, the template agent further comprises one or more of benzyldimethylamine, tetramethylammonium bromide, tetraethylammonium bromide, and tetrapropylammonium bromide. In some specific embodiments, the template agent comprises hexamethylammonium bromide and tetramethylammonium bromide. In some specific embodiments, the template agent comprises hexamethylammonium bromide and tetraethylammonium bromide. In some specific embodiments, the template agent comprises hexamethylammonium bromide and tetrapropylammonium bromide.

[0022] In some embodiments, the silicon source in the mixture is SiO2, the inorganic alkali source is the corresponding alkali metal oxide M2O, and the molar ratio of SiO2 to M2O is 1:0.2-0.5, for example, it can be 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5 or any value between them, preferably 1:(0.25-0.4).

[0023] In some embodiments, the silicon source in the mixture is SiO2, and the molar ratio of SiO2 to the template agent is 1:(0.1-0.6), for example, it can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6 or any value between them, preferably 1:(0.3-0.6).

[0024] In some embodiments, the silicon source in the mixture is SiO2, and the molar ratio of SiO2 to water is 1:10-80, for example, it can be 1:10, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:60, 1:70, 1:80 or any value between them, preferably 1:(25-40).

[0025] In some embodiments, the silicon source in the mixture is SiO2, the aluminum source is Al2O3, and the inorganic alkali source is the corresponding alkali metal oxide M2O, with a molar ratio of SiO2:Al2O3:M2O = 1:(0.001-0.003):(0.2-0.5).

[0026] In some embodiments, the silicon source in the mixture is SiO2 and the aluminum source is Al2O3, with a molar ratio of SiO2:Al2O3:template agent = 1:(0.001-0.003):(0.1-0.6).

[0027] In some embodiments, the silicon source in the mixture is SiO2, the aluminum source is Al2O3, and the inorganic alkali source is the corresponding alkali metal oxide M2O, with a molar ratio of SiO2:Al2O3:M2O:template = 1:(0.001-0.003):(0.2-0.5):(0.1-0.6).

[0028] In some embodiments, the silicon source in the mixture is SiO2, the aluminum source is Al2O3, and the inorganic alkali source is the corresponding alkali metal oxide M2O. The molar ratio of SiO2:Al2O3:M2O:template agent:H2O is 1:(0.001-0.003):(0.2-0.5):(0.1-0.6):(10-80).

[0029] In some preferred embodiments, in the mixture, the silicon source is SiO2, the aluminum source is Al2O3, and the inorganic alkali source is the corresponding alkali metal oxide M2O, with a molar ratio of SiO2:Al2O3:M2O:template agent:H2O = 1:(0.0012-0.0025):(0.25-0.4):(0.3-0.6):(25-40).

[0030] In this invention, the crystallization conditions, such as temperature, time, and pressure, are not particularly required. In some embodiments, the crystallization temperature is 120-200°C. In some embodiments, the crystallization temperature is 150-190°C. In some embodiments, the crystallization temperature is 170-190°C. In some embodiments, the crystallization time is 48-72 hours.

[0031] In some embodiments, the crystallization is carried out in a high-pressure reactor.

[0032] In some embodiments, the crystallization is carried out in a hypergravity reactor. In some specific embodiments, the rotational speed of the hypergravity reactor is 120-1500 rpm. In some specific embodiments, the rotational speed of the hypergravity reactor is 800-1200 rpm. In some specific embodiments, the feed rate of the hypergravity reactor is 50-200 mL / min. -1 In some specific embodiments, the feed rate of the centrifugal reactor is 80-150 mL / min. -1 .

[0033] In some embodiments, the method further includes an aging step of the mixture before crystallization. In this invention, the aging conditions, such as temperature and time, are not particularly required. In some embodiments, the aging is dynamic aging. In some specific embodiments, the aging temperature is 15-40°C, and the aging time is 8-16 hours. In some specific embodiments, the aging temperature is 15-40°C, and the aging time is 12-16 hours.

[0034] In some embodiments, the method further includes a step of post-processing the crystallization solution after crystallization. The post-processing refers to the process of treating the crystallization solution obtained after crystallization to obtain a molecular sieve. In some embodiments, the post-processing includes solid-liquid separation, washing, and heat treatment. In some embodiments, the heat treatment includes drying and calcination.

[0035] The present invention does not impose special requirements on the steps and conditions of solid-liquid separation, washing, and heat treatment, and these steps can be performed in any manner conventionally known in the art. Specifically, for example, the solid-liquid separation can be achieved through filtration, such as simply by vacuum filtering the obtained crystallized liquid. For washing, for example, washing with deionized water can be used. For drying, for example, 40-250°C, preferably 60-150°C, and for drying time, for example, 8-30 hours, preferably 10-20 hours. Drying can be carried out under normal pressure or under reduced pressure. In some specific embodiments, the drying temperature is 40-150°C, and the drying time is 8-20 hours. The calcination can be carried out in any manner conventionally known in the art; for example, the calcination temperature is generally 300-800°C, preferably 400-650°C, and the calcination time is generally 1-10 hours, preferably 3-6 hours. Furthermore, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere. In some specific embodiments, the calcination temperature is 500-600℃, and the calcination time is 3-6 hours.

[0036] Thirdly, the present invention provides the application of the sheet-like EU-1 molecular sieve described in the first aspect in catalysis, adsorption and ion exchange.

[0037] The sheet-like EU-1 molecular sieve of the present invention can be used as an adsorbent, for example, to separate at least one component from a mixture of multiple components in the gas or liquid phase. Accordingly, the at least one component can be partially or substantially completely separated from the mixture of various components, specifically by contacting the mixture with the sheet-like EU-1 molecular sieve to selectively adsorb the component.

[0038] In addition, the sheet-like EU-1 molecular sieve described in this invention can also be used as a catalyst, for example, for catalyzing reactions such as aromatic hydrocarbon conversion, methanol to propylene (MTP), and naphtha cracking.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The thin-film EU-1 molecular sieve of the present invention has a different morphology from the existing EU-1 molecular sieve, and has a high silicon-to-aluminum ratio, a large specific surface area, and high catalytic performance and stability.

[0041] 2. The preparation method of the present invention does not require the addition of seed crystals or the use of expensive organic bases. By selecting specific material ratios, thin-film EU-1 molecular sieves with pure phase crystals free of other impurities and high silicon-aluminum ratio can be obtained in one step.

[0042] 3. The preparation method of the present invention is simple, uses inexpensive and readily available raw materials, has high reaction efficiency, produces products with high crystallinity, has high stability, and is low in cost, making it suitable for industrial production. Attached Figure Description

[0043] Figure 1 The image shows the XRD pattern of the EU-1 molecular sieve prepared in Example 1 of this invention.

[0044] Figure 2 SEM image of the EU-1 molecular sieve prepared in Example 1 of this invention.

[0045] Figure 3 The XRD pattern of the EU-1 and ZSM-48 mixed molecular sieve prepared for Comparative Example 1.

[0046] Figure 4 SEM image of the rugby ball-shaped EU-1 molecular sieve prepared for Comparative Example 2. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0048] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0049] In this paper, the structure of the molecular sieve was determined by X-ray diffraction (XRD), which was measured using an X-ray powder diffractometer with a Cu-Kα source and a Kα1 wavelength λ = 1.5405980 angstroms. Nickel filter.

[0050] In this invention, an X'PertPRO X-ray powder diffractometer from Panaco GmbH, Netherlands, is used, with an operating voltage of 40kV, a current of 40mA, and a scanning range of 5–40°.

[0051] In this invention, the scanning electron microscope (SEM) images were obtained using a Japanese HITACHIS 4800 field emission scanning electron microscope, under the following test conditions: voltage 3kV, current 50mA.

[0052] Unless otherwise specified, all instruments, equipment, and reagents used in the following embodiments and comparative examples of this invention are commercially available. The centrifugal crystallization apparatus used was manufactured by Nanjing Hengge Water Treatment Technology Co., Ltd., and its operating parameters were: feed rate 50-200 mL / min. -1 The rotation speed is 120-1500 rpm, the crystallization temperature is 150-200℃, and the crystallization time is 48-72 h. In the example, the feed rate is 100 mL / min. -1 .

[0053] Example 1

[0054] 2.4g of sodium hydroxide was weighed and added to 65g of deionized water. After vigorous stirring, 0.023g of sodium aluminate was added and stirred until completely dissolved. Then, 10g of hexamethylammonium bromide was weighed and added to the mixed solution. After stirring for one hour, 5g of tetraethylammonium bromide was added until completely dissolved. After vigorous stirring for one hour, 15g of silica sol (40wt%) was added dropwise. The gel mixture was dynamically aged at room temperature for 12 hours and then transferred to a stainless steel high-pressure reactor with a polytetrafluoroethylene liner. Crystallization was carried out at 170℃ for 72 hours. After cooling, washing, and drying, EU-1 molecular sieve raw powder was obtained. The EU-1 molecular sieve raw powder was calcined in a muffle furnace at 550℃ for 5 hours to remove the template agent, thus obtaining EU-1 molecular sieve. X-ray diffraction (XRD) examination confirmed it to be pure-phase EU-1 molecular sieve, with a silicon-aluminum molar ratio of SiO2 / Al2O3 of 680.

[0055] Figure 1 The XRD pattern of the prepared EU-1 molecular sieve is shown below. Figure 1 It can be seen that the synthesized product is a pure-phase EU-1 molecular sieve.

[0056] Figure 2 SEM images of the prepared EU-1 molecular sieve, by Figure 2 It can be seen that the morphology of the synthesized EU-1 molecular sieve is different from that of the conventional EU-1 molecular sieve, which is rugby ball-shaped. It is a thin sheet with a sheet thickness of 35 nm.

[0057] Example 2

[0058] 3.2g of potassium hydroxide was weighed and added to 60g of deionized water. After stirring until completely dissolved, 0.04g of sodium aluminate was weighed and added to the mixture. After stirring for one hour, 13g of hexamethylammonium bromide was added until completely dissolved. Finally, 15g of silica sol (40wt%) was added dropwise. The gel mixture was dynamically aged at room temperature for 15 hours and then transferred to a high-gravity crystallization apparatus. Crystallization was carried out at 1000 rpm and 180℃ for 60 hours. After cooling, washing, and drying, EU-1 molecular sieve raw powder was obtained. The EU-1 molecular sieve raw powder was calcined in a muffle furnace at 560℃ for 3 hours to remove the template agent, resulting in flake-like EU-1 molecular sieve. X-ray diffraction (XRD) analysis confirmed it to be a pure-phase EU-1 molecular sieve, with a silicon-to-aluminum molar ratio of SiO2 / Al2O3 of 370.

[0059] Example 3

[0060] 2.4g of sodium hydroxide was weighed and added to 55g of deionized water. After vigorous stirring, 0.025g of sodium aluminate was added and stirred until completely dissolved. Then, 8g of hexamethylammonium bromide was weighed and added to the mixed solution. After stirring for one hour, 1.5g of tetramethylammonium bromide was added until completely dissolved. Finally, 15g of silica sol (40wt.%) was added dropwise. The gel mixture was dynamically aged at room temperature for 16 hours and then transferred to a high-gravity crystallization apparatus. Crystallization was carried out at 1000 rpm and 190℃ for 48 hours. After cooling, washing, and drying, EU-1 molecular sieve raw powder was obtained. The EU-1 molecular sieve raw powder was calcined in a muffle furnace at 580℃ for 3 hours to remove the template agent, resulting in flake-like EU-1 molecular sieve. X-ray diffraction (XRD) examination confirmed it to be pure-phase EU-1 molecular sieve, with a silicon-to-aluminum molar ratio of SiO2 / Al2O3 of 600.

[0061] Example 4

[0062] Weigh 3.0g of potassium hydroxide and add it to 60g of deionized water. Stir until completely dissolved. Then weigh 0.02g of sodium aluminate and add it to the mixture. After stirring for one hour, add 13g of hexamethylammonium bromide until completely dissolved. Finally, add 15g of silica sol (40wt%) dropwise. The gel mixture is dynamically aged at room temperature for 15 hours, then placed in a stainless steel high-pressure reactor with a polytetrafluoroethylene liner and statically crystallized at 180℃ for 60 hours. After cooling, washing, and drying, the molecular sieve powder is obtained. The molecular sieve powder is calcined in a muffle furnace at 560℃ for 3 hours to remove the template agent. X-ray diffraction (XRD) analysis confirms it as EU-1 molecular sieve, and SEM images show that the product has a plate-like structure.

[0063] Comparative Example 1

[0064] The method of Example 1 was followed, except that the template agent was different: hexamethylammonium bromide was not added, but only 5g of tetraethylammonium bromide template agent was added. All other conditions were the same. X-ray diffraction (XRD) test showed that it was a mixed molecular sieve of EU-1 and ZSM-48.

[0065] Figure 3 The XRD pattern of the EU-1 and ZSM-48 mixed molecular sieve prepared for Comparative Example 1. Figure 3 It can be seen that in addition to the characteristic peaks of EU-1 molecular sieve, the characteristic peaks of ZSM-48 molecular sieve also appeared, indicating that pure phase EU-1 molecular sieve cannot be synthesized.

[0066] Comparative Example 2

[0067] 1g of sodium hydroxide was weighed and added to 60g of deionized water, stirred until completely dissolved. Then, 0.1g of sodium aluminate was weighed and added to the mixture. After stirring for one hour, 5g of hexamethylammonium bromide was added, and the mixture was stirred vigorously for one hour. Finally, 15g of silica sol (40wt%) was added dropwise. The gel mixture was dynamically aged at room temperature for 16 hours, then placed in a stainless steel high-pressure reactor with a polytetrafluoroethylene liner and statically crystallized at 190℃ for 48 hours. After cooling, washing, and drying, the molecular sieve powder was obtained. The molecular sieve powder was calcined in a muffle furnace at 580℃ for 3 hours to remove the template agent. X-ray diffraction (XRD) analysis confirmed it to be EU-1 molecular sieve.

[0068] Figure 4 SEM images of the EU-1 molecular sieve prepared for Comparative Example 2; by Figure 4 It can be seen that the synthesized EU-1 molecular sieve has an oval shape.

[0069] Comparative Example 3

[0070] The only difference from Example 1 was that the amount of the template agent tetraethylammonium bromide was 10g. The final synthesized product was irregularly granular, without any plate-like structure.

[0071] Comparative Example 4

[0072] The only difference from Example 1 is that the amount of sodium hydroxide used is 0.8 g. X-ray diffraction (XRD) analysis showed that the final synthesized product was a mixed molecular sieve of EU-1 and ZSM-48.

[0073] Comparative Example 5

[0074] The only difference from Example 1 is that the amount of sodium hydroxide used is 4.8g. The final synthesized product is irregular granular, without any plate-like structure. As can be seen from Examples 1-4 above, the method of the present invention can obtain EU-1 pure phase molecular sieves with different silicon-aluminum molar ratios by controlling the proportions of inorganic alkali source, silicon oxide, alumina, template agent, etc.

[0075] Analysis of Experimental Results: A comparison of the results of Comparative Example 1 and Example 1 shows that this invention, using only tetraethylammonium bromide as a template agent without adding hexamethylammonium bromide, cannot synthesize a pure-phase EU-1 molecular sieve. Compared to Examples 1-4, Comparative Examples 2-5 require that the proportions of inorganic base source, silica, alumina, and template agent be controlled within appropriate ranges; otherwise, a plate-like pure-phase EU-1 molecular sieve cannot be obtained.

[0076] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A sheet-like EU-1 molecular sieve, wherein the sheet thickness is 20-50 nm; the silicon-aluminum molar ratio (SiO2 / Al2O3) of the molecular sieve is 350-700.

2. The molecular sieve according to claim 1, characterized in that, The specific surface area of ​​the molecular sieve is greater than 200 m². 2 ∙g -1 .

3. A method for preparing the sheet-like EU-1 molecular sieve of claim 1 or 2, comprising the following steps: A mixture containing an inorganic alkali source, an aluminum source, a template agent, a silicon source, and water was crystallized to obtain plate-like EU-1 molecular sieves. In the mixture, the silicon source is SiO2, the aluminum source is Al2O3, and the inorganic alkali source is the corresponding alkali metal oxide M2O. The molar ratio of SiO2:Al2O3:M2O:template:H2O is 1:(0.001-0.003):(0.2-0.5):(0.1-0.6):(10-80). The template agent includes hexamethylammonium bromide, and optionally, the template agent also includes one or more of benzyldimethylamine, tetramethylammonium bromide, tetraethylammonium bromide, and tetrapropylammonium bromide.

4. The method according to claim 3, characterized in that, The molar ratio of SiO2 to Al2O3 is 1:(0.0012-0.0025).

5. The method according to claim 3, characterized in that, The inorganic alkali source is at least one of alkali metal oxides, alkali metal hydroxides, and alkali metal carbonates; and / or, The silicon source is selected from one or more of silica sol, water glass, and silicate esters; and / or, The aluminum source is selected from one or more of sodium aluminate, aluminum nitrate nonahydrate, boehmite, and aluminum isopropoxide.

6. The method according to claim 5, characterized in that, The inorganic alkaline source is at least one of lithium hydroxide, sodium hydroxide, and potassium hydroxide.

7. The method according to any one of claims 3-6, characterized in that, The molar ratio of SiO2 to M2O is 1:(0.25-0.4); and / or the molar ratio of SiO2 to template agent is 1:(0.3-0.6); and / or the molar ratio of SiO2 to water is 1:(25-40).

8. The method according to any one of claims 3-6, characterized in that, In the mixture, the molar ratio of SiO2:Al2O3:M2O:template:H2O = 1:(0.0012-0.0025):(0.25-0.4):(0.3-0.6):(25-40).

9. The method according to any one of claims 3-6, characterized in that, The crystallization temperature is 120-200℃; the crystallization time is 48-72 h.

10. The method according to claim 9, characterized in that, The crystallization temperature is 150-190℃.

11. The method according to any one of claims 3-6, characterized in that, The crystallization is carried out in a hypergravity reactor.

12. The method according to claim 11, characterized in that, The rotational speed of the hypergravity reactor is 120-1500 rpm.

13. The method according to claim 12, characterized in that, The rotational speed of the hypergravity reactor is 800-1200 rpm.

14. The method according to claim 11, characterized in that, The feed rate of the centrifugal reactor is 50-200 mL / min. -1 .

15. The method according to claim 14, characterized in that, The feed rate of the centrifugal reactor is 80-150 mL / min. -1 .

16. The method according to any one of claims 3-6, characterized in that, The method further includes: aging the mixture before crystallization, and / or post-processing the crystallized liquid after crystallization, wherein the post-processing includes solid-liquid separation, washing, drying and calcination.

17. The method according to claim 16, characterized in that, The aging temperature is 15-40℃, and the aging time is 8-16 h.

18. The method according to claim 16, characterized in that, The drying temperature is 40-150℃; the drying time is 8-20h.

19. The method according to claim 16, characterized in that, The roasting temperature is 500-600℃; the roasting time is 3-6 h.

20. The application of the sheet-like EU-1 molecular sieve according to claim 1 or 2 in catalysis, adsorption and ion exchange.

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