A layered mordenite molecular sieve and a method for making the same

Abstract

The application provides a layered mordenite molecular sieve and a preparation method thereof. The content of four-coordinated framework aluminum in the layered mordenite molecular sieve provided by the application is greater than or equal to 80% of the total aluminum content. The process procedure of the application is simple, the preparation efficiency is high, the cost is low, the layered mordenite molecular sieve synthesized by the application has high crystallinity, a high proportion of four-coordinated framework aluminum, and a large micropore specific surface, and is more suitable for popularization and application in industry.

Description

Technical Field

[0001] This application belongs to the field of catalysts, specifically relating to a layered mordenite molecular sieve and its preparation method. Background Technology

[0002] Microporous molecular sieves are crucial solid acid catalytic materials in the petrochemical industry. Their primary catalytically active acid sites are distributed within the pores. Therefore, besides their acidic characteristics, the unique pore structure of the molecular sieve and the cavities formed by their interconnections play a decisive role in the formation of intermediate products and the direction of the reaction pathway—this is known as the shape selectivity of the molecular sieve. Specifically, the catalytic reaction at the acidic sites within the micropores to obtain a specific product is first limited by the pore size; molecules smaller than the pore diameter can freely enter and exit, otherwise, catalytic reactions are difficult to occur. Secondly, the pore length of the molecular sieve severely hinders the diffusion of raw material and product molecules. Pore lengths of several micrometers can lead to the aggregation of large molecules or the occurrence of secondary reactions, resulting in increased carbon deposition and rapid deactivation of the molecular sieve. Furthermore, the occurrence of numerous secondary reactions within the pores drastically reduces the selectivity of the target product.

[0003] Mordenite (MOR) is a type of microporous zeolite catalytic material with parallel elliptical twelve-membered rings (0.65 × 0.70 nm) and eight-membered rings (0.26 × 0.57 nm) with straight channels along the c-axis. Due to its excellent catalytic performance in reactions such as toluene disproportionation, hydrocracking, alkylation, aromatic isomerization, and alkyl transfer, it has been widely used in the petrochemical field. However, traditionally synthesized mordenite particles are relatively large, typically in the micrometer range (>1 μm), resulting in a small external surface area. This hinders the diffusion and mass transfer of large molecular reactants in catalytic reactions, leading to low catalytic efficiency. Furthermore, secondary reactions easily occur within the micropores, reducing the selectivity of the target product and even causing catalyst deactivation due to carbon deposition. Based on the shortcomings of micron-sized mordenite in catalytic reactions, the synthesis of nano-mordenite with high diffusion properties has become a research hotspot in zeolite synthesis. However, granular nano-mordenite still suffers from low external surface area and poor accessibility of reactive sites.

[0004] A special synthesis method can be used to synthesize mordenite with a layered morphology. This type of mordenite has a near-two-dimensional structure, a short c-axis dimension, sufficient exposure of surface acidic sites, and strong accessibility of reactants on the catalyst surface. CN201610908241.5 discloses a method for synthesizing plate-like nano-mordenite molecular sieves, which can prepare plate-like mordenite with a c-axis thickness of 10-40 nm through hydrothermal synthesis, but the template agent used has a relatively complex structure. In 2017, Researcher Shen Wenjie et al. from the Dalian Institute of Chemical Physics used a single-headed quaternary ammonium [C 16 H 33 -N +-(CH3)2-C4H8-N + Using [-(CH3)2-benzylammonium(Bza-4-16)] as a structure directing agent, mordenite molecular sieves with a thickness of 20–40 nm along the c-axis (twelve-membered ring channel) were obtained. This effectively shortened the length of the twelve-membered and eight-membered ring channels, greatly enhancing the molecular diffusion ability. When these molecular sieves were applied to the carbonylation reaction of dimethyl ether, it was found that the catalytic activity of the thin-film molecular sieve was far superior to that of traditional MOR molecular sieves. In 2020, Researcher Wu Peng et al. from East China Normal University, by controlling the silicon-to-aluminum ratio and using the bifunctional amphiphilic structure directing agent [C...], obtained... 16 H 33 -N + A three-dimensional sheet-like MOR molecular sieve with a thickness of only 11 nm along the b-axis was synthesized using [(CH3)2-C2H4-N(CH3)2Br(C16-2-O)]. Compared with conventional MOR, this molecular sieve exhibits extremely high ethylene selectivity in the methanol-to-olefins conversion reaction, while effectively inhibiting coking and enhancing catalyst lifetime. Therefore, the synthesis of sheet-like mordenite zeolite with high diffusion performance, uniform aluminum distribution, and complete microporous structure using commonly used, inexpensive, and readily available organic amine template agents is of greater practical significance in industry. Summary of the Invention

[0005] To address the issues of complex and costly existing synthetic thin-film MOR processes, this application provides a layered mordenite with a single aluminum distribution and a complete microporous structure, along with its low-cost preparation method.

[0006] In a first aspect, this application provides a layered mordenite molecular sieve, wherein the content of four-coordinated framework aluminum in the molecular sieve is greater than or equal to 80% of the total aluminum content.

[0007] The high content of tetracoordinated framework aluminum in mordenite molecular sieves can improve the utilization rate of aluminum atoms and have higher atom economy. At the same time, the tetracoordinated framework aluminum forms a (Si-O-Al)-OH bridged hydroxyl structure with neighboring silicon atoms, bringing strong bronsted acidic sites, which are more conducive to chemical reactions.

[0008] In this application, the aluminum content of the four-coordinate framework is: 27 The percentage of the combined peak area of ​​around 55 ppm (tetracoordinated framework aluminum) and around 0 ppm (hexacoordinated framework aluminum) in the Al MAS NMR spectrum.

[0009] In some embodiments, the tetracoordinated framework aluminum content in the molecular sieve is 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or any value between them. In some embodiments, the tetracoordinated framework aluminum content in the molecular sieve is greater than or equal to 85% of the total aluminum content. In some embodiments, the tetracoordinated framework aluminum content in the molecular sieve is greater than or equal to 90% of the total aluminum content. In some embodiments, the tetracoordinated framework aluminum content in the molecular sieve is greater than or equal to 95% of the total aluminum content.

[0010] In some embodiments, the molecular sieve has a lamellar morphology.

[0011] In some embodiments, the molecular sieve has a plate-like structure in the ab plane.

[0012] In some embodiments, the molecular sieve has a size of 0.2-5 μm along the ab plane, for example, 0.3 μm, 0.5 μm, 0.7 μm, 1.0 μm, 1.3 μm, 1.5 μm, 1.7 μm, 2.0 μm, 2.3 μm, 2.5 μm, 2.7 μm, 3.0 μm, 3.3 μm, 3.5 μm, 3.7 μm, 4.0 μm, 4.3 μm, 4.5 μm, 4.7 μm, or any value between them.

[0013] In some embodiments, the thickness of the molecular sieve along the c-axis is 10-500 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 230 nm, 250 nm, 270 nm, 300 nm, 330 nm, 350 nm, 370 nm, 400 nm, 430 nm, 450 nm, 470 nm, or any value between them. In some embodiments, the thickness of the molecular sieve along the c-axis is 10-200 nm.

[0014] In some embodiments, the total specific surface area of ​​the molecular sieve is greater than or equal to 450 m². 2 / g, for example, 460m 2 / g、480m 2 / g、500m 2 / g、520m 2 / g、540m 2 / g、560m 2 / g、580m 2 / g、600m2 / g、650m 2 / g or any value between them. In some cases, the total specific surface area of ​​the molecular sieve is 470-550 m². 2 / g. In some embodiments, the total specific surface area of ​​the molecular sieve is 500-550 m² / g. 2 / g.

[0015] In some embodiments, the microporous specific surface area of ​​the molecular sieve accounts for at least 70% of the total specific surface area, for example, 72%, 74%, 76%, 78%, 80%, 81%, 83%, 85%, 87%, 90%, 93%, 95%, or any value between therewith. In some embodiments, the microporous specific surface area of ​​the molecular sieve accounts for 70%-90% of the total specific surface area. In some embodiments, the microporous specific surface area of ​​the molecular sieve accounts for 75-80% of the total specific surface area. In some embodiments, the microporous specific surface area of ​​the molecular sieve accounts for 70%-75% of the total specific surface area.

[0016] In some embodiments, the total pore volume of the molecular sieve is greater than or equal to 0.2 cm³. 3 / g, for example, 0.21cm 3 / g, 0.22cm 3 / g, 0.23cm 3 / g, 0.24cm 3 / g, 0.25cm 3 / g, 0.26cm 3 / g, 0.27cm 3 / g, 0.28cm 3 / g, 0.29cm 3 / g, 0.30cm 3 / g, 0.31cm 3 / g, 0.33cm 3 / g, 0.35cm 3 / g or any value between them. In some embodiments, the total pore volume of the molecular sieve is 0.25-0.28 cm³. 3 / g.

[0017] In some embodiments, the micropore volume of the molecular sieve accounts for at least 70% of the total pore volume, for example, 72%, 74%, 76%, 78%, 80%, 81%, 83%, 85%, 87%, 90%, 93%, 95%, 97%, or any value between therewith. In some embodiments, the micropore volume of the molecular sieve accounts for 70%-95% of the total pore volume. In some embodiments, the micropore volume of the molecular sieve accounts for 70-80% of the total pore volume.

[0018] Secondly, this application provides a method for preparing layered mordenite molecular sieves, comprising:

[0019] S1: Provides a mixture including an aluminum source, a silicon source, an alkali source, a first template agent, a second template agent, and water, as well as optional seed crystals;

[0020] S2: Crystallize the mixture from step S1;

[0021] The first template includes one or more compounds represented by Formula I or Formula II:

[0022]

[0023] In Formula I, X1 is selected from hydroxyl or halogen, and R and R1 may be the same or different, each independently selected from C1-C6 straight-chain alkyl, C3-C6 branched-chain alkyl or C3-C12 cycloalkyl.

[0024]

[0025] In Formula II, R2, R3 and R4 may be the same or different, each independently selected from hydrogen, a straight-chain alkyl group of C1-C6 or a branched alkyl group of C3-C6, and at least one of R2, R3 and R4 is not hydrogen;

[0026] The second template agent includes one or more of the compounds shown in Formula III or Formula IV:

[0027]

[0028] In Formula III, X2 is selected from hydroxyl or halogen, R' is selected from C1-C6 straight-chain alkyl or C3-C6 branched alkyl, and R4 is selected from C8-C20 straight-chain alkyl or C8-C20 branched alkyl.

[0029]

[0030] In Formula IV, Y1 and Y2 may be the same or different, each independently selected from CH2 or NH, R5 is selected from hydrogen, amino, C1-C6 straight-chain alkyl or C3-C6 branched alkyl, and at least one of Y1, Y2 and R5 is selected from NH or amino, a is 0, 1, 2 or 3, and b is 0, 1, 2 or 3.

[0031] This application demonstrates that by employing a specific combination of template agents during the synthesis of mordenite molecular sieves, the colloidal properties of the synthesized gel can be effectively altered, thereby inducing the growth of plate-like crystals.

[0032] In some embodiments, in Formula I, X1 is selected from hydroxyl, chlorine or bromine; R and R1 are the same and are both selected from C1-C6 straight-chain alkyl groups, such as methyl, ethyl, n-propyl or n-butyl.

[0033] In some embodiments, R and R1 in Formula I are different, where R is selected from C1-C6 straight-chain alkyl groups, such as methyl, ethyl, n-propyl or n-butyl, and R1 is selected from C8-C12 cycloalkyl groups, such as cyclooctane, cyclononane, cyclodecane or adamantane.

[0034] In some embodiments, in Formula II, R2, R3 and R4 may be the same or different, each independently selected from hydrogen or C1-C6 straight-chain alkyl, C3-C6 branched alkyl, such as methyl, ethyl, n-propyl, isopropyl, isobutyl, tert-butyl or n-butyl.

[0035] In some embodiments, in Formula II, R2, R3, and R4 may be the same or different, each independently selected from hydrogen or a C1-C6 straight-chain alkyl group, such as methyl, ethyl, n-propyl, or n-butyl.

[0036] In some embodiments, the compound represented by Formula I includes: N,N,N-trimethyl-1-adamantyl ammonium hydroxide, tetraethylammonium bromide, tetramethylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetraethylammonium bromide, and tetraethylammonium hydroxide.

[0037] In some embodiments, the compound represented by Formula II includes triethylamine and di-n-propylamine.

[0038] In some embodiments, the first template agent is selected from one or more of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, tetraethylammonium bromide, tetramethylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium hydroxide, triethylamine, and di-n-propylamine.

[0039] In some embodiments, the first template agent is selected from one or two of N,N,N-trimethyl-1-adamantylammonium hydroxide, triethylamine, and di-n-propylamine.

[0040] In some embodiments, in Formula III, R' is selected from C1-C4 straight-chain alkyl or C3-C4 branched alkyl, such as methyl, ethyl, n-propyl, isopropyl, isobutyl, tert-butyl or n-butyl.

[0041] In some embodiments, Formula III is selected from straight-chain alkyl groups of C10-C18 or branched-chain alkyl groups of C10-C18, such as n-decane, isodecane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, and n-octadecane.

[0042] In some embodiments, in Formula III, X2 is selected from hydroxyl, chlorine or bromine; R' is selected from C1-C6 straight-chain alkyl groups; and R4 is selected from C10-C18 straight-chain alkyl groups.

[0043] In some embodiments, the compound represented by Formula III includes hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyltrimethylammonium hydroxide.

[0044] In some embodiments, in Formula IV, Y1 and Y2 are the same and are both selected from CH2, R5 is selected from an amino group, or at least one of Y1 and Y2 is selected from NH, and R5 is selected from hydrogen or a C1-C6 straight-chain alkyl group, such as methyl, ethyl, n-propyl or n-butyl.

[0045] In some embodiments, the compound represented by Formula IV includes cyclohexylamine, piperazine, piperidine, and hexamethyleneimine.

[0046] In some embodiments, the second template agent is selected from one or more of cyclohexylamine, piperazine, piperidine, hexamethyleneimine, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyltrimethylammonium hydroxide.

[0047] In some embodiments, the second template agent comprises at least one of the compounds shown in Formula III and at least one of the compounds shown in Formula IV.

[0048] In some embodiments, the second template agent comprises at least one selected from hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyltrimethylammonium hydroxide, and at least one selected from cyclohexylamine, piperazine, piperidine, and hexamethyleneimine.

[0049] In some embodiments, the silicon source in the mixture, calculated as SiO2, has a molar ratio of the first template agent to the silicon source of 0.02-0.6, for example, 0.05, 0.1, 0.13, 0.15, 0.17, 0.2, 0.23, 0.25, 0.27, 0.3, 0.33, 0.35, 0.37, 0.4, 0.43, 0.45, 0.47, 0.5, 0.53, 0.55, 0.57, or any value between them. In some embodiments, the molar ratio of the first template agent to the silicon source is 0.1-0.4.

[0050] In some embodiments, the silicon source in the mixture is SiO2, and the molar ratio of the second template agent to the silicon source is 0.01-0.8, for example, 0.05, 0.1, 0.13, 0.15, 0.17, 0.2, 0.23, 0.25, 0.27, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or any value between them. In some embodiments, the molar ratio of the second template agent to the silicon source is 0.02-0.2.

[0051] In some embodiments, the silicon source is SiO2 and the aluminum source is Al2O3 in the mixture, and the molar ratio of the silicon source to the aluminum source is 10-120, for example, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 or any value between them. In some embodiments, the molar ratio of the silicon source to the aluminum source is 10-30.

[0052] In some embodiments, the silicon source in the mixture is SiO2, the alkali source is M2O, M is selected from alkali metals, such as sodium or potassium, and the molar ratio of the alkali source to the silicon source is 0.02-0.4, for example, 0.05, 0.1, 0.13, 0.15, 0.17, 0.2, 0.23, 0.25, 0.27, 0.3, 0.33, 0.35, 0.37 or any value between them. In some embodiments, the molar ratio of the alkali source to the silicon source is 0.05-0.1.

[0053] In some embodiments, the silicon source, calculated as SiO2, has a water-to-silicon source molar ratio of 5-50, for example, 10, 15, 20, 25, 30, 35, 40, 45, or any value between them. In some embodiments, the water-to-silicon source molar ratio is 7-20.

[0054] In some embodiments, the silicon source in the mixture is SiO2, and the mass of the seed crystal is 0.01-5% of the mass of the silicon source, for example, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, or 4.5%. In some embodiments, the mass of the seed crystal is 0.1-1% of the mass of the silicon source.

[0055] In some embodiments, the second template agent comprises at least one compound of Formula III and at least one compound of Formula IV, wherein the molar ratio of the compound of Formula III to the compound of Formula IV is 0.1-10, for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, or any value between them. In some embodiments, the molar ratio of the compound of Formula III to the compound of Formula IV is 2-5. In some embodiments, the molar ratio of the compound of Formula III to the compound of Formula IV is 0.1-1.

[0056] In some embodiments, step S1, providing a mixture comprising an aluminum source, a silicon source, an alkali source, a first template agent, a second template agent, and water, and optionally seed crystals, includes:

[0057] S11: Mix the alkali source, aluminum source and water to obtain the first mixture;

[0058] S12: Mix the first mixture with the first template agent and a portion of the second template agent to obtain the second mixture;

[0059] S13: Mix the second mixture with the remaining portion of the second template agent to obtain the third mixture;

[0060] S14: Mix the third mixture with the silicon source and the seed crystal to obtain the mixture.

[0061] In some embodiments, in step S12, a portion of the second template agent is selected from the compound shown in Formula IV, and in step S13, the remaining portion of the second template agent is selected from the compound shown in Formula III.

[0062] In some embodiments, step S2 includes a first crystallization process and a second crystallization process performed sequentially.

[0063] In some embodiments, the temperature of the first crystallization treatment is 30°C-140°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or 130°C. In some embodiments, the time of the first crystallization treatment is 0.5h-144h, for example, 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, 110h, 120h, or 130h.

[0064] In some embodiments, the temperature of the second crystallization treatment is 100℃-240℃, for example, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, or 230℃. In some embodiments, the time of the second crystallization treatment is 0.5h-144h, for example, 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, 110h, 120h, or 130h.

[0065] In some embodiments, the preparation method further includes washing, drying and calcining the crystallization product of step S2 to obtain the molecular sieve.

[0066] In some embodiments, the drying temperature is 60-120°C, such as 70°C, 80°C, 90°C, 100°C, or 110°C. In some embodiments, the drying time is 2-12 hours, such as 4 hours, 6 hours, 8 hours, or 10 hours.

[0067] In some embodiments, the calcination temperature is 500-650°C, for example 530°C, 550°C, 600°C, or 630°C. In some embodiments, the calcination time is 4-10 hours, for example 5 hours, 7 hours, or 9 hours.

[0068] In some embodiments, the silicon source is selected from one or more of silica sol, silica gel, methyl orthosilicate, ethyl orthosilicate, silica fume, water glass, and hexadecyltrimethoxysilane.

[0069] In some embodiments, the aluminum source is selected from one or more of aluminum isopropoxide, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate.

[0070] In some embodiments, the alkali source is selected from one or more alkali metal hydroxides; in other embodiments, the alkali source is selected from one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0071] In some embodiments, the seed crystals are selected from mordenite zeolite.

[0072] In some embodiments, the preparation method includes the following specific steps:

[0073] Step (1): Mix the alkali source, aluminum source, silicon source, first template agent, second template agent, seed crystal and water to form initial gel A;

[0074] Step (2): The initial gel is aged under static or dynamic conditions at a certain temperature, such as 30℃-140℃, for a certain time, such as 0.5h-144h, to obtain gel B.

[0075] Step (3): Gel B is crystallized and grown at a certain temperature, such as 100℃-240℃, under static or dynamic conditions for a certain time, such as 0.5h-144h, to obtain thin-sheet mordenite molecular sieve raw powder;

[0076] Step (4): Wash, dry and calcine the raw powder of thin-layer mordenite molecular sieve to obtain thin-layer mordenite molecular sieve.

[0077] Compared with the prior art, this application has the following advantages:

[0078] The process described in this application is simple, efficient, and inexpensive. The synthesized MOR molecular sieve has high crystallinity, a four-coordinated framework aluminum ratio, and a large microporous specific surface area, making it more suitable for industrial application. Attached Figure Description

[0079] Figure 1 The image shows the XRD pattern of the mordenite molecular sieve in Example 1.

[0080] Figure 2 This is a SEM image of the mordenite molecular sieve in Example 1.

[0081] Figure 3 The image shows the HR-TEM image of the mordenite molecular sieve in Example 1.

[0082] Figure 4 The image shown is a SAED diagram of the mordenite molecular sieve in Example 1.

[0083] Figure 5 The mordenite molecular sieve in Example 1 27 Al MAS NMR image.

[0084] Figure 6 The nitrogen physical adsorption-desorption isotherm of the mordenite molecular sieve in Example 1 is shown.

[0085] Figure 7 The image shows the XRD pattern of the mordenite molecular sieve in Example 2.

[0086] Figure 8 For the mordenite molecular sieve in Example 2 27 Al MAS NMR image.

[0087] Figure 9 The image shows the XRD pattern of the zeolite molecular sieve in Comparative Example 1.

[0088] Figure 10 For the zeolite molecular sieve in Comparative Example 1 27 Al MAS NMR image. Detailed Implementation

[0089] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application in any way. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and technologies have also been described in numerous publications.

[0090] 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.

[0091] In the context of this specification, including the following examples and comparative examples, XRD data were obtained using a Bruker AXSD8 Advance X-ray diffractometer, Germany, under Cu Kα radiation (40 kV, 40 mA). The test step size is 0.02, the step time is 12.6s, and the test 2θ range is 5-50°.

[0092] In the context of this specification, including the following examples and comparative examples, SEM images were obtained using a Japanese HITACHI S4800 field emission scanning electron microscope under test conditions of 3 kV and 10 μA.

[0093] In the context of this specification, including in the following examples and comparative examples, the TEM images and SAEDs were provided by Tecnai G, FEI Corporation, USA. 2 The results were obtained using an F20 S-Twin field emission transmission electron microscope. The test conditions were: operating voltage 200kV, point resolution 0.24nm, and tilt angles ±40° in the X direction and ±30° in the Y direction.

[0094] In the context of this specification, including in the following embodiments and comparative examples, 27 Al MAS NMR was obtained using a Bruker AVANCE III 400WB (9.4T) solid-state NMR spectrometer. The testing conditions were as follows: 27 The Al MAS NMR resonance frequency was 104.3 MHz. A 4 mm rotor was used at a rotation speed of 12 kHz, with a 1 M Al(NO3)3 aqueous solution as the external standard for chemical shift. The test was performed using a single pulse with a 10° pulse width of 0.5 μs and a relaxation delay of 0.3 s.

[0095] Among them, the proportion of aluminum in the four-coordinated framework is 27 The percentage of the peak area at 55 ppm in the Al MAS NMR spectrum compared to the sum of the peak areas at 55 ppm and 0 ppm.

[0096] In the context of this specification, including in the following examples and comparative examples, pore structure parameters, such as total pore volume, micropore volume, total specific surface area, and micropore specific surface area, were obtained by measuring the nitrogen physisorption-desorption isotherms of the molecular sieve using a physisorption analyzer (such as the TriStar 3000 physisorption analyzer from Micron Instruments, Inc.), and then calculating them using the BET method and the t-plot method. The total specific surface area refers to the total area per unit mass of sample.

[0097] The experimental conditions for nitrogen physical adsorption-desorption were as follows: measurement temperature -169℃, and molecular sieve pretreated in vacuum at 300℃ for 10 hours before measurement.

[0098] Unless otherwise specified, the pressures mentioned in the following examples and comparative examples are gauge pressures, and % represents mass percentage.

[0099] The present application will be further described below with reference to the embodiments, but the embodiments do not limit the scope of protection of the present application.

[0100] Example 1

[0101] Mix 0.67g KOH and 0.18g Al(OH)3, add 27g water and stir to dissolve. Then add 0.50g piperazine (second template agent) and 1.01g di-n-propylamine (first template agent) as a mixed template agent and dissolve evenly. Next, add 2.85g of the second template agent, hexadecyltrimethylammonium hydroxide, and stir evenly. Finally, add 3g silica and 0.03g mordenite seed crystals and stir evenly to form a gel precursor.

[0102] In the gel precursor, the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali source as K2O. The molar ratios of each material are: SiO2 / Al2O3 = 43, K2O / SiO2 = 0.12, first template agent / SiO2 = 0.2, second template agent piperazine / SiO2 = 0.1, second template agent hexadecyltrimethylammonium hydroxide / SiO2 = 0.2, total second template agent / SiO2 = 0.3, and water / SiO2 = 30. The silicon source is calculated as SiO2, and the mordenite seed crystal accounts for 1% of the silicon source mass.

[0103] The gel precursor was aged at 45°C for 1 day, then transferred to an oven and crystallized at 150°C under autogenous pressure for 3 days. The crystallized product was cooled, filtered, washed, and dried to obtain the zeolite molecular sieve product.

[0104] Figure 1The image shows the XRD pattern of the zeolite molecular sieve product. X-ray diffraction analysis of the product indicates that its structure is mordenite molecular sieve.

[0105] Figure 2 Here are the SEM images of the zeolite molecular sieve products, from... Figure 2 As can be seen, the product has a sheet-like morphology, with a thickness of 10-50 nm and a size of 1-3 μm.

[0106] Figure 3 and Figure 4 The images shown are HR-TEM and SAED images of the zeolite molecular sieve product. High-resolution transmission electron microscopy and selected area electron diffraction reveal that the exposed surface of the product is the (001) plane.

[0107] Figure 5 Zeolite molecular sieve products 27 The Al MAS NMR spectrum shows a peak at 55 ppm, which is attributed to a four-coordinated framework aluminum, and a peak at 0 ppm, which is attributed to a six-coordinated framework aluminum. The four-coordinated framework aluminum accounts for 98%.

[0108] Figure 6 The nitrogen physical adsorption-desorption isotherm of the zeolite molecular sieve product is shown, indicating that the BET specific surface area of ​​the zeolite molecular sieve product is 552 m². 2 / g, of which the microporous specific surface area is 402m 2 / g; zeolite molecular sieve products have a density of 0.26cm. 3 / g pore volume, of which the micropore volume is 0.20cm 3 / g.

[0109] Example 2

[0110] Mix 0.67g KOH and 0.18g Al(OH)3, add 27g water and stir to dissolve. Then add 0.50g piperazine (second template agent) and 2.11g N,N,N-trimethyl-1-adamantyl ammonium hydroxide (first template agent) as a mixed template agent and dissolve evenly. Next, add 2.85g of the second template agent, hexadecyltrimethoxyammonium hydroxide, and stir evenly. Finally, add 3g silica and 0.03g mordenite seed crystals and stir evenly to form a gel precursor.

[0111] In the gel precursor, the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali source as K2O. The molar ratios of each material are: SiO2 / Al2O3 = 43, K2O / SiO2 = 0.12, first template agent / SiO2 = 0.2, second template agent piperazine / SiO2 = 0.1, second template agent N,N,N-trimethyl-1-adamantyl ammonium hydroxide / SiO2 = 0.2, total second template agent / SiO2 = 0.3, and water / SiO2 = 30. The silicon source is calculated as SiO2, and the mordenite seed crystal accounts for 1% of the silicon source mass.

[0112] The gel precursor was aged at 45°C for 1 day, then transferred to an oven and crystallized at 150°C under autogenous pressure for 3 days. The crystallized product was cooled, filtered, washed, and dried to obtain the zeolite molecular sieve product.

[0113] Figure 7 The image shows the XRD pattern of the zeolite molecular sieve product. X-ray diffraction analysis of the product indicates that its structure is mordenite molecular sieve.

[0114] Figure 8 Zeolite molecular sieve products 27 Al MAS NMR spectrum, in which aluminum accounts for 89% of the four-coordinated framework.

[0115] SEM images of zeolite molecular sieve products and Figure 1 Similarly, they have a thin, sheet-like morphology, with a thickness of 20-100 nm and a size of 1-3 μm.

[0116] The BET specific surface area of ​​the zeolite molecular sieve product is 483 m². 2 / g, of which the microporous specific surface area is 385m 2 / g; pore volume is 0.26cm³ 3 / g, of which the micropore volume is 0.21cm³ 3 / g.

[0117] Example 3

[0118] The only difference from Example 1 is that the mass of the first template agent, di-n-propylamine, is 0.26 g, that is, in the gel precursor, the ratio of the first template agent to SiO2 is 0.05.

[0119] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 10-50 nm and a size of 1-3 μm. The aluminum content of the four-coordinate framework is 81%.

[0120] The BET specific surface area of ​​the zeolite molecular sieve product is 476 m². 2 / g, of which the microporous specific surface area is 373m 2 / g; pore volume is 0.23cm 3 / g, of which the micropore volume is 0.18cm³3 / g.

[0121] Example 4

[0122] The only difference from Example 1 is that the mass of the first template agent, di-n-propylamine, is 2.02 g, that is, in the gel precursor, the ratio of the first template agent to SiO2 is 0.4.

[0123] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 50-250 nm and a size of 1-3 μm. The aluminum content of the four-coordinate framework is 92%.

[0124] The BET specific surface area of ​​the zeolite molecular sieve product is 485 m². 2 / g, of which the microporous specific surface area is 379m 2 / g; pore volume is 0.26cm³ 3 / g, of which the micropore volume is 0.22cm³ 3 / g.

[0125] Example 5

[0126] The only difference from Example 1 is that the mass of the first template agent, di-n-propylamine, is 3.03 g, that is, in the gel precursor, the ratio of the first template agent to SiO2 is 0.6.

[0127] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 100-500 nm and a size of 1-3 μm. The aluminum content of the four-coordinate framework is 92%.

[0128] The BET specific surface area of ​​the zeolite molecular sieve product is 462 m². 2 / g, of which the microporous specific surface area is 377m 2 / g; pore volume is 0.26cm³ 3 / g, of which the micropore volume is 0.23cm³ 3 / g.

[0129] Example 6

[0130] The only difference from Example 1 is that, while keeping the total amount of the second template agent unchanged, the second template agent is only 1.5g piperazine, that is, in the gel precursor, the second template agent piperazine / SiO2 = 0.3.

[0131] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 20-50 nm and a size of 1-3 μm. The aluminum content of the four-coordinate framework is 88%.

[0132] The BET specific surface area of ​​the zeolite molecular sieve product is 477 m². 2 / g, of which the microporous specific surface area is 413m 2 / g; pore volume is 0.25cm3 / g, of which the micropore volume is 0.21cm³ 3 / g.

[0133] Example 7

[0134] The only difference from Example 1 is that, while keeping the total amount of the second template agent unchanged, the second template agent is only 4.3g of hexadecyltrimethoxyammonium hydroxide, that is, in the gel precursor, the ratio of the second template agent hexadecyltrimethoxyammonium hydroxide to SiO2 is 0.3.

[0135] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 20-100 nm and a size of 1-3 μm. The aluminum content of the four-coordinate framework is 89%.

[0136] The BET specific surface area of ​​the zeolite molecular sieve product is 492 m². 2 / g, of which the microporous specific surface area is 407m 2 / g; pore volume is 0.26cm³ 3 / g, of which the micropore volume is 0.21cm³ 3 / g.

[0137] Example 8

[0138] The only difference from Example 1 is that the first template agent is 1.48g of tetraethylammonium hydroxide, and the ratio of the first template agent to SiO2 in the gel precursor is 0.2.

[0139] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 10-50 nm and a size of 1-3 μm. The aluminum content of the four-coordinate framework is 87%.

[0140] The BET specific surface area of ​​the zeolite molecular sieve product is 498 m². 2 / g, of which the microporous specific surface area is 407m 2 / g; pore volume is 0.25cm 3 / g, of which the micropore volume is 0.21cm³ 3 / g.

[0141] Example 9

[0142] Mix 0.67g KOH and 0.18g Al(OH)3, add 27g water and stir to dissolve. Then add 0.50g piperazine (second template agent), 1.01g di-n-propylamine (first template agent), and 2.85g hexadecyltrimethoxyammonium hydroxide (second template agent) and stir until homogeneous. Finally, add 3g silica and 0.03g mordenite seed crystals and stir until homogeneous to form a gel precursor.

[0143] In the gel precursor, the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali source as K2O. The molar ratios of each material are: SiO2 / Al2O3 = 43, K2O / SiO2 = 0.12, first template agent / SiO2 = 0.2, second template agent piperazine / SiO2 = 0.1, second template agent hexadecyltrimethylammonium hydroxide / SiO2 = 0.2, total second template agent / SiO2 = 0.3, and water / SiO2 = 30. The silicon source is calculated as SiO2, and the mordenite seed crystal accounts for 1% of the silicon source mass.

[0144] The rest is the same as in Example 1.

[0145] The final zeolite molecular sieve product has a plate-like morphology with a thickness of 3-5 nm and a size of 2-5 μm. The aluminum content of the four-coordinate framework is 89%.

[0146] The BET specific surface area of ​​the zeolite molecular sieve product is 472 m². 2 / g, of which the microporous specific surface area is 403m 2 / g; pore volume is 0.25cm 3 / g, of which the micropore volume is 0.23cm³ 3 / g.

[0147] Comparative Example 1

[0148] Mix 0.67g KOH and 0.18g Al(OH)3, add 27g water and stir to dissolve. Then add 1.01g di-n-propylamine as a template agent and dissolve evenly. Subsequently, add 3g silica and stir evenly to form a gel precursor.

[0149] In the gel precursor, the silicon source is SiO2, the aluminum source is Al2O3, the alkali source is K2O, and the molar ratio of each material is SiO2 / Al2O3 = 43, K2O / SiO2 = 0.12, template agent / SiO2 = 0.2, and water / SiO2 = 30.

[0150] The gel precursor was aged at 45°C for 1 day, then transferred to an oven and crystallized at 150°C under autogenous pressure for 3 days. The crystallized product was cooled, filtered, washed, and dried to obtain the zeolite molecular sieve product.

[0151] Figure 9 The image shows the XRD pattern of the zeolite molecular sieve product. X-ray diffraction analysis of the product indicates that its structure is a MOR molecular sieve.

[0152] Figure 10 For zeolite molecular sieve products 27 Al MAS NMR image, in which the four-coordinated framework aluminum accounts for 71%.

[0153] The preferred embodiments of this application have been described in detail above; however, this application is not limited thereto. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in this application and are all within the protection scope of this application.

Claims

1. A layered mordenite molecular sieve, characterized in that, The molecular sieve has a four-coordinated framework aluminum content greater than or equal to 80% of the total aluminum content, preferably greater than or equal to 85%, and more preferably greater than or equal to 95%.

2. The molecular sieve according to claim 1, characterized in that, The molecular sieve has a lamellar morphology; Preferably, the molecular sieve has a plate-like structure in the ab plane; More preferably, the molecular sieve has a size of 0.2-5 μm along the ab plane and a thickness of 10-500 nm along the c-axis, preferably 10-200 nm.

3. The molecular sieve according to claim 1 or 2, characterized in that, The total specific surface area of ​​the molecular sieve is greater than or equal to 450 m². 2 / g, preferably 470-550m 2 / g; and / or The molecular sieve has a microporous specific surface area accounting for at least 70% of the total specific surface area, preferably 70%-90%, more preferably 70-75%; and / or The total pore volume of the molecular sieve is greater than or equal to 0.2 cm³. 3 / g, preferably 0.25-0.28cm 3 / g; and / or The micropore volume of the molecular sieve accounts for at least 70% of the total pore volume, preferably 70%-95%, and more preferably 70%-80%.

4. A method for preparing layered mordenite molecular sieves, comprising: S1: Provides a mixture including an aluminum source, a silicon source, an alkali source, a first template agent, a second template agent, and water, as well as optional seed crystals; S2: Crystallize the mixture from step S1; The first template includes one or more compounds represented by Formula I or Formula II: In Formula I, X1 is selected from hydroxyl or halogen, and R and R1 may be the same or different, each independently selected from C1-C6 straight-chain alkyl, C3-C6 branched-chain alkyl or C3-C12 cycloalkyl. In Formula II, R2, R3 and R4 may be the same or different, each independently selected from hydrogen, a straight-chain alkyl group of C1-C6 or a branched alkyl group of C3-C6, and at least one of R2, R3 and R4 is not hydrogen; The second template agent includes one or more of the compounds shown in Formula III or Formula IV: In Formula III, X2 is selected from hydroxyl or halogen, R' is selected from C1-C6 straight-chain alkyl or C3-C6 branched alkyl, and R4 is selected from C8-C20 straight-chain alkyl or C8-C20 branched alkyl. In Formula IV, Y1 and Y2 may be the same or different, each independently selected from CH2 or NH, R5 is selected from hydrogen, amino, C1-C6 straight-chain alkyl or C3-C6 branched alkyl, and at least one of Y1, Y2 and R5 is selected from NH or amino, a is 0, 1, 2 or 3, and b is 0, 1, 2 or 3.

5. The preparation method according to claim 4, characterized in that, In Formula I, X1 is selected from hydroxyl, chlorine, or bromine; R and R1 are the same, both selected from C1-C6 straight-chain alkyl groups, or R and R1 are different, with R selected from C1-C6 straight-chain alkyl groups and R1 selected from C8-C12 cycloalkyl groups; and / or In Formula II, R2, R3, and R4 may be the same or different, and each is independently selected from hydrogen or a straight-chain alkyl group of C1-C6; and / or; Preferably, the first template agent is selected from one or more of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, tetraethyl ammonium bromide, tetramethyl ammonium hydroxide, tetramethyl ammonium bromide, tetraethyl ammonium hydroxide, tetrapropyl ammonium bromide, tetrapropyl ammonium hydroxide, tetraethyl ammonium bromide, tetraethyl ammonium hydroxide, triethylamine, and di-n-propylamine, and more preferably from one or two of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, triethylamine, and di-n-propylamine.

6. The preparation method according to claim 4 or 5, characterized in that, In Formula III, X2 is selected from hydroxyl, chlorine, or bromine; R' is selected from C1-C6 straight-chain alkyl groups; R4 is selected from C10-C18 straight-chain alkyl groups; and / or In Formula IV, Y1 and Y2 are the same and are both selected from CH2, R5 is selected from amino, or at least one of Y1 and Y2 is selected from NH, and R5 is selected from hydrogen or a straight-chain alkyl group of C1-C6. Preferably, the second template agent is selected from one or more of cyclohexylamine, piperazine, piperidine, hexamethyleneimine, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyltrimethylammonium hydroxide; More preferably, the second template agent comprises at least one of the compounds shown in Formula III and at least one of the compounds shown in Formula IV. For example, the second template agent includes at least one selected from hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide and dodecyltrimethylammonium hydroxide and at least one selected from cyclohexylamine, piperazine, piperidine and hexamethyleneimine.

7. The preparation method according to any one of claims 4-6, characterized in that, In the mixture, the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali source as M2O, where M is selected from alkali metals, such as sodium or potassium. The molar ratio of the first template agent to the silicon source is 0.02-0.6, preferably 0.1-0.4; and / or The molar ratio of the second template agent to the silicon source is 0.01-0.8, preferably 0.02-0.2; and / or The molar ratio of silicon source to aluminum source is 10-120, preferably 10-30; and / or The molar ratio of the alkali source to the silicon source is 0.02-0.4, preferably 0.05-0.1; and / or The molar ratio of water to silicon source is 5-50, preferably 7-20; and / or The mass of the seed crystal is 0.01-5% of the mass of the silicon source, preferably 0.1-1%; Preferably, the second template agent comprises at least one of the compounds shown in Formula III and at least one of the compounds shown in Formula IV, wherein the molar ratio of the compounds shown in Formula III and the compounds shown in Formula IV is preferably 0.1-10, and more preferably 2-5.

8. The preparation method according to any one of claims 4-7, characterized in that, In step S1, providing a mixture comprising an aluminum source, a silicon source, an alkali source, a first template agent, a second template agent, and water, and optionally seed crystals, includes: S11: Mix the alkali source, aluminum source and water to obtain the first mixture; S12: Mix the first mixture with the first template agent and a portion of the second template agent to obtain the second mixture; S13: Mix the second mixture with the remaining portion of the second template agent to obtain the third mixture; S14: Mix the third mixture with the silicon source and the seed crystal to obtain the mixture; Preferably, in step S12, a portion of the second template agent is selected from the compound shown in Formula IV, and in step S13, the remaining portion of the second template agent is selected from the compound shown in Formula III.

9. The preparation method according to any one of claims 4-8, characterized in that, In step S2, the crystallization process includes a first crystallization process and a second crystallization process performed sequentially. Preferably, the temperature of the first crystallization treatment is 30℃-140℃, and the time of the first crystallization treatment is 0.5h-144h; the temperature of the second crystallization treatment is 100℃-240℃, and the time of the second crystallization treatment is 0.5h-144h; and / or The preparation method further includes washing, drying, and calcining the crystallization product from step S2 to obtain the molecular sieve. Preferably, the drying temperature is 60-120℃ and the drying time is 2-12h, and the calcination temperature is 500-650℃ and the calcination time is 4-10h.

10. The preparation method according to any one of claims 4-9, characterized in that, The silicon source is selected from one or more of silica sol, silica gel, methyl orthosilicate, ethyl orthosilicate, silica fume, water glass, and hexadecyltrimethoxysilane; and / or The aluminum source is selected from one or more of aluminum isopropoxide, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate; and / or The alkali source is selected from one or more alkali metal hydroxides, preferably from one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide; and / or The seed crystals are selected from mordenite zeolite.

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