阅读说明：本技术 分子筛及其制备方法和应用 (Molecular sieve and preparation method and application thereof ) 是由 齐静 张堃 李云 李伟 雍晓静 武燕娟 王杰 刘琰 关翀 金政伟 张伟 于 2021-01-12 设计创作，主要内容包括：本发明涉及催化领域,公开了分子筛及其制备方法和应用,该方法包括：(1)将硅源、铝源、模板剂和溶剂混合,得到预晶化液；(2)将所述预晶化液依次进行老化、晶化、干燥和焙烧后得到分子筛；其中,所述模板剂含有碱和含氟季铵盐。该方法使用碱和含氟季铵盐作为模板剂来制备分子筛,在该模板剂、硅源和铝源的协同作用下,所得的分子筛的晶体的结晶度较高,粒度分布均匀,制备过程简单。(The invention relates to the field of catalysis, and discloses a molecular sieve, a preparation method and application thereof, wherein the method comprises the following steps: (1) mixing a silicon source, an aluminum source, a template agent and a solvent to obtain a pre-crystallization liquid; (2) sequentially aging, crystallizing, drying and roasting the pre-crystallization liquid to obtain a molecular sieve; wherein the template agent contains alkali and fluorine-containing quaternary ammonium salt. According to the method, alkali and fluorine-containing quaternary ammonium salt are used as template agents to prepare the molecular sieve, and under the synergistic effect of the template agents, a silicon source and an aluminum source, the obtained molecular sieve has the advantages of high crystallinity, uniform particle size distribution and simple preparation process.)

1. A method for preparing a molecular sieve, the method comprising:

(1) mixing a silicon source, an aluminum source, a template agent and a solvent to obtain a pre-crystallization liquid;

(2) sequentially aging, crystallizing, drying and roasting the pre-crystallization liquid to obtain a molecular sieve;

wherein the template agent contains alkali and fluorine-containing quaternary ammonium salt.

2. The method of claim 1, wherein the weight ratio of the silicon source, the aluminum source, and the templating agent is 1: 0.0002-0.05: 0.01 to 0.5, preferably 1: 0.005-0.03: 0.05-0.2.

3. The method according to claim 1 or 2, wherein the weight ratio of the base to the fluorine-containing quaternary ammonium salt in the template is 1: 0.5 to 5, preferably 1: 1-3;

preferably, the base is selected from the group consisting of those having the general structural formula [ R₁R₂R₃R₄N]⁺X^-、R₁′R₂′R₃' N andwherein R is₁、R₂、R₃And R₄Identical or different and are each independently selected from H or alkyl, preferably alkyl having 1 to 6 carbon atoms, X is halogen or OH, preferably selected from Cl, Br or I; r₁′、R₂' and R₃' are identical or different and are each independently selected from H or alkyl, preferably alkyl having from 2 to 4 carbon atoms; more preferably, the base is at least one selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium bromide, tetrapropylammonium bromide, diethylamine, n-butylamine, ammonia and pyridine;

preferably, the fluorine-containing quaternary ammonium salt has a structural general formula of [ R₁″R₂″R₃″R₄″N]⁺M^-Wherein R is₁″、R₂″、R₃"and R₄"identical or different and each is independently selected from alkyl groups, preferably alkyl groups having 1 to 4 carbon atoms, M is F; more preferably, the fluorine-containing quaternary ammonium salt is tetraethylammonium fluoride and/or tetrapropylammonium fluoride.

4. The method of any one of claims 1-3, wherein the silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, trimethylethoxysilane, and polysiloxane; preferably ethyl orthosilicate.

5. The process of any one of claims 1-4, wherein the aluminum source is a water soluble aluminum salt; preferably, the aluminum source is selected from at least one of sodium metaaluminate, aluminum isopropoxide, aluminum sulfate, and aluminum nitrate; more preferably, the aluminum source is aluminum isopropoxide.

6. The method according to any one of claims 1-5, wherein the solvent is water, preferably deionized water.

7. The method of any one of claims 1-6, wherein the mixing is performed under conditions of sonication and stirring;

preferably, the conditions of the ultrasound include: the frequency is 25-150kHz, the temperature is 5-40 ℃, and the time is 0.5-5 h;

preferably, the conditions of the stirring include: the rotating speed is 50-200r/min, and the time is 0.5-5 h.

8. The method of any one of claims 1 to 7, wherein the solvent is used in an amount such that the pH of the pre-crystallized liquid is in the range of 10 to 12.

9. The method of any of claims 1-8, wherein the aging condition comprises: the temperature is 30-50 ℃ and the time is 6-24 h;

and/or, the crystallization conditions include: the temperature is 150 ℃ and 190 ℃, and the time is 12-72 h;

and/or, the drying conditions include: the temperature is 110-150 ℃, and the time is 10-15 h;

and/or, the roasting conditions include: heating to 500-550 ℃ at a heating rate of 0.5-2.5 ℃/min, and then roasting for 5-8h at the temperature.

10. A molecular sieve, characterized in that it is prepared by a process according to any one of claims 1 to 9.

11. Use of the molecular sieve of claim 10 in catalytic cracking, aromatization, alkylation, disproportionation, membrane separation and chemical sensors.

Technical Field

The invention relates to the field of catalysis, in particular to a molecular sieve and a preparation method and application thereof.

Background

The ZSM-5 molecular sieve is synthesized for the first time by the American Mobile company in 1972, and is widely applied to chemical reactions such as catalytic cracking, aromatization, alkylation, disproportionation and the like due to the unique MFI type topological structure and the oleophilic and hydrophobic surface. The non-aggregation molecular sieve with the particle size less than 100nm is called as a nano molecular sieve, and compared with the traditional micron-sized or submicron-sized molecular sieve, the nano molecular sieve has the advantages of shorter diffusion channel, higher pore aperture ratio, larger external specific surface area and the like, so that the nano molecular sieve can be used as a catalytic and adsorption material with excellent performance. With the increase of the depth and the breadth of resource utilization, the nano molecular sieve ZSM-5 molecular sieve is gradually applied industrially, such as in the processes of methylcyclohexane cracking, n-hexadecane isomerization, cumene cracking and the like. Besides, the nano ZSM-5 molecular sieve can also be assembled into a film for membrane separation, chemical sensors and the like.

At present, the synthesis technology of the nano ZSM-5 molecular sieve mainly focuses on an extremely concentrated system method, a xerogel method, an organic solvothermal method, an ionothermal synthesis method, a space-limited method and a hydrothermal synthesis method.

The synthesis of coke jade and the like (coke jade and the like, the synthesis of a fluorine-containing system nano ZSM-5 molecular sieve, [ C ]// 18 th national molecular sieve academic congresson (upper) 0.) discloses that active silica gel prepared by performing special hydrolysis and drying processes on tetraethoxysilane is used as a silicon source, a fluorine-containing quaternary ammonium salt is used as a template agent (equivalent to the fluorine-containing quaternary ammonium salt of the application), the number of crystal nuclei is increased, the crystallization rate is reduced by adopting a dynamic crystallization method under the conditions of lower water-silicon ratio and lower crystallization temperature by adjusting the alkalinity of the system, and the first-time synthesis of the fluorine-containing ZSM-5 molecular sieve with crystal grains smaller than 100nm (about 50nm on average) needs to prepare the silica gel as the silicon source. However, when the fluorine-containing quaternary ammonium salt is used as a template agent, the ZSM-5 molecular sieve has low crystallinity and uneven particle size distribution. In addition, to adjust the pH, inorganic bases such as sodium hydroxide, potassium hydroxide, etc. are typically added to the fluorine-containing templating agent system, resulting in the need for more water to wash subsequently.

Although the nano ZSM-5 molecular sieve has the advantages, the opening degree of the pore opening of the outer surface is large and the crystallinity is low due to the nano-scale particle size, and the shape selectivity is reduced and the byproducts are increased in the catalytic reaction process. Therefore, many researches in recent years are focused on how to reduce the surface crystal defects of the nano ZSM-5 molecular sieve, mainly on surface organic functional group modification, chemical vapor deposition, chemical liquid deposition and the like. The preparation method of the composite molecular sieve with ZSM-5 as the core and other molecular sieves as the shells is also proved to improve the catalytic performance, but the preparation process is more complicated and is not beneficial to industrial amplification.

Disclosure of Invention

The invention aims to solve the technical problems of complicated preparation process, uneven particle size distribution and low crystal crystallinity of the molecular sieve in the prior art, and provides the molecular sieve and the preparation method and application thereof.

The inventor of the invention unexpectedly finds that the molecular sieve is prepared by using alkali and the fluorine-containing quaternary ammonium salt as the template agent, and under the synergistic effect of the template agent, the silicon source and the aluminum source, the technical problems of low crystallinity and uneven particle size distribution of the molecular sieve when the fluorine-containing quaternary ammonium salt is used as the template agent alone can be solved, and the obtained molecular sieve has the advantages of high crystallinity, even particle size distribution and simple preparation process.

In order to achieve the above object, a first aspect of the present invention provides a method for preparing a molecular sieve, the method comprising:

(1) mixing a silicon source, an aluminum source, a template agent and a solvent to obtain a pre-crystallization liquid;

(2) sequentially aging, crystallizing, drying and roasting the pre-crystallization liquid to obtain a molecular sieve;

wherein the template agent contains alkali and fluorine-containing quaternary ammonium salt.

The invention provides a molecular sieve, which is prepared by the method.

In a third aspect the invention provides the use of the above molecular sieve in catalytic cracking, aromatization, alkylation, disproportionation, membrane separation and chemical sensors.

According to the preparation method of the molecular sieve, alkali and the fluorine-containing quaternary ammonium salt are used as the template agent to prepare the molecular sieve, and under the synergistic effect of the template agent, the silicon source and the aluminum source, the obtained molecular sieve has the advantages of high crystallinity, uniform particle size distribution and simple preparation process.

Drawings

FIG. 1 is an SEM image of a molecular sieve obtained according to example 1 of the present invention;

FIG. 2 is an SEM image of a molecular sieve obtained according to example 2 of the present invention;

FIG. 3 is an SEM image of a molecular sieve obtained according to example 8 of the present invention;

FIG. 4 is an SEM image of a molecular sieve obtained according to comparative example 1;

FIG. 5 is an XRD pattern of the molecular sieve obtained according to example 1 of the present invention;

FIG. 6 is an XRD pattern of the molecular sieve obtained in accordance with example 2 of the present invention;

FIG. 7 is an XRD pattern of the molecular sieve obtained in accordance with example 8 of the present invention;

figure 8 is an XRD pattern of the molecular sieve obtained in comparative example 1.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In a first aspect, the present invention provides a method for preparing a molecular sieve, the method comprising:

(1) mixing a silicon source, an aluminum source, a template agent and a solvent to obtain a pre-crystallization liquid;

(2) sequentially aging, crystallizing, drying and roasting the pre-crystallization liquid to obtain a molecular sieve;

wherein the template agent contains alkali and fluorine-containing quaternary ammonium salt.

In some embodiments of the present invention, in order to obtain a nano molecular sieve with high crystallinity and dispersibility in a wide range of silicon-aluminum ratio, the weight ratio of the silicon source, the aluminum source and the template agent is preferably 1: 0.0002-0.05: 0.01 to 0.5, more preferably 1: 0.005-0.03: 0.05-0.2.

In some embodiments of the present invention, in the template agent, for the purpose of adjusting the pH of the system while not containing an inorganic base, the weight ratio of the base to the fluorine-containing quaternary ammonium salt is preferably 1: 0.5 to 5, more preferably 1: 1-3.

In some embodiments of the present invention, the base is not limited as long as it can be combined with the fluorine-containing quaternary ammonium salt to adjust the pH, and may be, for example, an organic base and/or ammonia, and preferably, the base is selected from the group consisting of those having the general structural formula [ R₁R₂R₃R₄N]⁺X^-、R₁′R₂′R₃' N andwherein R is₁、R₂、R₃And R₄Identical or different and are each independently selected from H or alkyl, preferably alkyl having 1 to 6 carbon atoms, X is halogen or OH, preferably selected from Cl, Br or I; r₁′、R₂' and R₃' are identical or different and are each independently selected from H or alkyl, preferably alkyl having from 2 to 4 carbon atoms. More preferably, the base is at least one selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium bromide, tetrapropylammonium bromide, diethylamine, n-butylamine, ammonia and pyridine.

In some embodiments of the present invention, the fluorine-containing quaternary ammonium salt has a general structural formula of [ R₁″R₂″R₃″R₄″N]⁺M^-Wherein R is₁″、R₂″、R₃"and R₄"identical or different and each is independently selected from alkyl groups, preferably alkyl groups having 1 to 4 carbon atoms, M is F; more preferably, the fluorine-containing quaternary ammonium salt is tetraethylammonium fluoride and/or tetrapropylammonium fluoride.

In some embodiments of the present invention, the kind of the silicon source is not limited as long as the silicon source can be provided for the synthesis of the molecular sieve, and preferably, the silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, trimethylethoxysilane and polysiloxane; more preferably, tetraethoxysilane.

In some embodiments of the present invention, the aluminum source is not limited as long as it can provide an aluminum source for the synthesis of the molecular sieve, and preferably, the aluminum source is a water-soluble aluminum salt. More preferably, the aluminum source is selected from at least one of sodium metaaluminate, aluminum isopropoxide, aluminum sulfate, and aluminum nitrate. Further preferably, the aluminum source is aluminum isopropoxide.

In some embodiments of the present invention, the solvent used to dissolve the silicon source, aluminum source, and templating agent is water, preferably deionized water.

In some embodiments of the present invention, to prevent aggregation of particles in the pre-crystallized liquid, a uniform pre-crystallized liquid is obtained. The mixing is carried out under conditions of ultrasound and agitation. The conditions of the ultrasound include: the frequency of the ultrasound is preferably 25-150 kHz. The temperature of the ultrasound is preferably 5 to 40 ℃. The time of ultrasound is preferably 0.5 to 5 h. The stirring conditions include: the rotation speed of the stirring is preferably 50-200 r/min. The stirring time is preferably 0.5 to 5 hours.

In the invention, in order to obtain crystals with better crystallization effect, the mixing is carried out in two steps, firstly, under the condition of ultrasonic stirring (the ultrasonic frequency is 25-150kHz, the temperature is 5-40 ℃, and the time is preferably 0.5-5h, wherein the stirring condition comprises that an aluminum source, a silicon source and a solvent are mixed to form a uniform system under the stirring condition that the rotating speed is 50-200r/min and the time is 0.5-5h, and then a template agent is added into the obtained uniform system to form a system A; then under the condition of ultrasonic stirring (the ultrasonic frequency is 25-150kHz, the temperature is 5-40 ℃, the time is preferably 0.5-5h, and the stirring condition comprises the stirring rotating speed is 50-200r/min, and the time is 0.5-5h), the temperature of the system A is raised to 70-90 ℃, and deionized water is added at any time to ensure that the pH value of the system is 10-12, so as to form a uniform system B. The process can remove the organic oxygen-containing compound generated in the hydrolysis process of the silicon source, thereby avoiding the organic oxygen-containing compound from influencing the generation of crystals.

In some embodiments of the present invention, the solvent is preferably used in an amount such that the pH of the pre-crystallized liquid is 10 to 12.

In some embodiments of the present invention, in order to ensure the stability of the subsequent crystallization process and obtain a more uniform particle size distribution, the aging conditions include: the temperature of aging is preferably 30 to 50 ℃. The aging time is preferably 6-24 h.

In some embodiments of the invention, the crystallization conditions comprise: the temperature of crystallization is preferably 150-190 ℃. The crystallization time is preferably 12 to 72 hours.

In some embodiments of the present invention, the drying apparatus is not limited, and drying means well known to those skilled in the art may be used, and the drying conditions include: the temperature of drying is preferably 110-150 ℃. The drying time is preferably 10-15 h.

In some embodiments of the present invention, the dried product is calcined by a drying means well known to those skilled in the art, and the calcination is performed in an air atmosphere, preferably, the calcination conditions include: heating to 500-550 ℃ at a heating rate of 0.5-2.5 ℃/min, and then roasting for 5-8h at the temperature.

According to a preferred embodiment of the invention, after an aluminum source, a silicon source and a solvent are mixed to form a homogeneous system under the condition of ultrasonic stirring (the frequency of ultrasonic is 25-150kHz, the temperature is 5-40 ℃, and the time is preferably 0.5-5h, and the stirring condition comprises the rotating speed of stirring is 50-200r/min, and the time is 0.5-5h), a template agent is added into the obtained homogeneous system to form a system A (wherein the weight ratio of the silicon source, the aluminum source and the template agent is controlled to be 1: 0.0002-0.05: 0.01-0.5); then heating the system A to 70-90 ℃ under the condition of ultrasonic stirring (the ultrasonic frequency is 25-150kHz, the temperature is 5-40 ℃, the time is preferably 0.5-5h, and the stirring condition comprises the stirring rotating speed is 50-200r/min, and the time is 0.5-5h), deionized water is added at any time to ensure that the pH value of the system is 10-12 to form a uniform system B, and then aging (the temperature is 30-50 ℃ and the time is 6-24h), crystallizing (the temperature is 150-.

The invention provides a molecular sieve, which is prepared by the method.

In a third aspect the invention provides the use of the above molecular sieve in catalytic cracking, aromatization, alkylation, disproportionation, membrane separation and chemical sensors.

The present invention will be described in detail below by way of examples.

Example 1

Under the condition of ultrasonic (frequency of 25Hz, temperature of 15 ℃ and time of 2h) stirring (rotating speed of 100r/min and time of 2h), 3.57g of aluminum sulfate is dissolved in 1100g of water, then under the same condition, 714g of ethyl orthosilicate is added, after a uniform system is formed, 17.85g of tetrapropylammonium fluoride and 17.85g of n-butylamine are added, and a system A is formed. Under the condition of ultrasonic stirring (the frequency is 25Hz, the temperature is 15 ℃ and the time is 2h), the temperature of the system A is raised to 80 ℃, deionized water is added at any time, the pH value of the system is kept at 10, and finally a uniform system B is formed. Aging B at 40 deg.C for 6 hr, placing into hydrothermal crystallization kettle, and crystallizing at 180 deg.C for 24 hr to obtain final product system C. And filtering and washing the C, drying at 120 ℃ for 12h, then heating from 20 ℃ to 525 ℃ at the heating rate of 1 ℃/min in the air atmosphere, and roasting at 525 ℃ for 8h to obtain the molecular sieve.

Example 2

Under the condition of ultrasonic (frequency of 150Hz, temperature of 40 ℃ and time of 0.5h) stirring (rotating speed of 50r/min and time of 0.5h), 21.42g of aluminum sulfate is dissolved in 1100g of water, then under the same condition, 714g of ethyl orthosilicate is added, after a uniform system is formed, 107.1g of tetrapropylammonium fluoride and 35.7g of tetrapropylammonium hydroxide are added, and a structural system A is formed. Under the condition of ultrasonic stirring (the frequency is 150Hz, the temperature is 40 ℃ and the time is 0.5h), the temperature of the system A is raised to 80 ℃, deionized water is added at any time, the pH value of the system is kept at 12, and finally a uniform system B is formed. Aging B at 30 deg.C for 12 hr, placing into hydrothermal crystallization kettle, crystallizing at 160 deg.C for 48 hr to obtain final product system C. And filtering and washing the C, drying at 110 ℃ for 15h, then heating from 20 ℃ to 500 ℃ at the heating rate of 2.5 ℃/min in the air atmosphere, and roasting at 500 ℃ for 5h to obtain the molecular sieve.

Example 3

Under the condition of ultrasonic stirring (the frequency is 100Hz, the temperature is 5 ℃ and the time is 3h), 12.5g of aluminum sulfate is dissolved in 1100g of water, 714g of ethyl orthosilicate is added under the same condition, 59.26g of tetrapropyl ammonium fluoride and 30g of tetrapropyl ammonium hydroxide are added after a homogeneous system is formed, and a formation system A is formed. Under the condition of ultrasonic stirring (the frequency is 100Hz, the temperature is 5 ℃ and the time is 3h), the temperature of the system A is raised to 80 ℃, deionized water is added at any time, the pH value of the system is kept at 11, and finally a uniform system B is formed. Aging B at 50 deg.C for 24 hr, placing into hydrothermal crystallization kettle, crystallizing at 150 deg.C for 72 hr to obtain final product system C. And filtering and washing the C, drying at 150 ℃ for 10h, then heating from 20 ℃ to 550 ℃ at the heating rate of 0.5 ℃/min in the air atmosphere, and roasting at 550 ℃ for 6h to obtain the molecular sieve.

Example 4

Preparation of a molecular sieve was carried out in the same manner as in example 1, except that the weight of aluminum sulfate was 0.14g, the weight of ethyl orthosilicate was 714g, the weight of tetrapropylammonium fluoride was 3.57g and the weight of n-butylamine was 3.57 g.

Example 5

Preparation of a molecular sieve was carried out in the same manner as in example 1, except that the weight of aluminum sulfate was 35.7g, the weight of ethyl orthosilicate was 714g, the weight of tetrapropylammonium fluoride was 178.5g and the weight of n-butylamine was 178.5 g.

Example 6

Preparation of a molecular sieve was conducted in accordance with the method of example 1, except that the weight of tetrapropylammonium fluoride was 11.9g and the weight of n-butylamine was 23.8 g.

Example 7

Preparation of a molecular sieve was conducted in accordance with the method of example 1, except that the weight of tetrapropylammonium fluoride was 29.75g and the weight of n-butylamine was 5.95 g.

Example 8

Preparation of a molecular sieve was carried out as in example 1, except that tetrapropylammonium fluoride was replaced with ammonium fluoride and n-butylamine was replaced with tetrapropylammonium hydroxide.

Comparative example 1

Preparation of the molecular sieve was carried out as in example 1, except that tetrapropylammonium fluoride was replaced with n-butylamine having the same weight.

Comparative example 2

Preparation of the molecular sieves was carried out as in example 1, except that n-butylamine was replaced with tetrapropylammonium fluoride in the same amount by weight.

Test example

The molecular sieves obtained in examples and comparative examples were subjected to a scanning electron microscope test using a FEIQuanta 200F field emission scanning electron microscope under an acceleration voltage of 30 kV. From the test results, it can be seen that the molecular sieves obtained in the examples have uniform particle sizes and nanoparticles having particle sizes of 100nm or less, and the molecular sieves obtained in the comparative examples have non-uniform particle sizes and particles having particle sizes of more than 1 μm. The SEM pictures obtained in example 1 are shown in FIG. 1, example 2 is shown in FIG. 2, example 8 is shown in FIG. 3, and comparative example 1 is shown in FIG. 4.

The molecular sieves obtained in the examples and comparative examples were subjected to X-ray powder diffractometry using a Japanese-type automatic D-MAX/IIA X-ray diffractometer under CuK α target, 30kV/20mA, scanning range of 5 to 35 ℃ and speed of 8/min. From the test results, it can be seen that the molecular sieves obtained in the examples and comparative examples are of MFI structure, and the obtained XRD patterns have characteristic peaks at 2 theta of 7.92 degrees, 8.80 degrees, 14.78 degrees, 23.10 degrees, 23.90 degrees and 24.40 degrees. The X-ray diffraction pattern obtained in example 1 is shown in FIG. 5, the X-ray diffraction pattern obtained in example 2 is shown in FIG. 6, the X-ray diffraction pattern obtained in example 8 is shown in FIG. 7, the X-ray diffraction pattern obtained in comparative example 1 is shown in FIG. 8, and the relative crystallinities of the molecular sieves of the examples and comparative examples obtained by the test are shown in Table 1.

TABLE 1

Numbering	Relative degree of crystallinity/%)
		Example 1	99.28
Example 2	99.02
		Example 3	99.65
Examples4	97.85
		Example 5	97.32
Example 6	97.03
		Example 7	97.41
Example 8	95.65
		Comparative example 1	88.13
Comparative example 2	90.12

According to the test results, it can be seen that in examples 1 to 8, by using the technical scheme of the present application and using alkali and a fluorine-containing quaternary ammonium salt as a template to prepare the molecular sieve, under the synergistic effect of the template, a silicon source and an aluminum source, the obtained crystals of the molecular sieve have high crystallinity, uniform particle size distribution and a simple preparation process. Comparative examples 1-2 did not adopt the technical scheme of this application, and the obtained molecular sieve crystals were of lower crystallinity, non-uniform particle size distribution, and agglomerated.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.