A method for synthesizing a multi-level pore thin sheet structure ZSM-5 molecular sieve

Abstract

The application discloses a synthesis method of a multi-level hole thin slice structure ZSM-5 molecular sieve, and comprises the following steps: S1, mixing, stirring a silicon source, an alkali source, an aluminum source, a micropore template agent and water to form a ZSM-5 molecular sieve precursor gel; S2, adding a mesopore template agent and a crystal growth inhibitor into the ZSM-5 molecular sieve precursor gel, then performing a crystallization reaction, filtering, washing, drying and calcining the product after the reaction is completed to obtain the multi-level hole thin slice structure ZSM-5 molecular sieve. The multi-level hole thin slice structure ZSM-5 molecular sieve is directly synthesized by using a hydrothermal synthesis method, glucose is introduced into the system to control the product to form a thin slice structure, a mesopore template agent containing a silicon aluminum species is introduced at the same time, the silicon aluminum species and the micelles formed by self-assembly of the silicon aluminum species are mixed into a homogeneous gel, the mesopores are formed by removing the micelles after crystallization and high-temperature calcination.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst technology, and particularly relates to a synthesis method of a multi-stage hole thin sheet structure ZSM-5 molecular sieve. BACKGROUND

[0002] ZSM-5 zeolite is a high-silicon microporous zeolite with a three-dimensional cross-pore system synthesized by the United States Mobil Company in 1972. Since it has good thermal stability, hydrothermal stability and shape-selective catalytic performance, it is widely used in the field of petroleum chemical industry. However, due to the small pore size (0.54 nm x 0.56 nm) of ZSM-5 zeolite, on the one hand, macromolecules are difficult to enter the pore, and on the other hand, the diffusion resistance of macromolecules is large, which often leads to the occurrence of side reactions, thereby limiting its application range to a certain extent.

[0003] Reducing the size of ZSM-5 molecular sieve in the b-axis direction to the nanometer level to construct a thin sheet structure is an effective method to slow down the diffusion resistance. Ryoo et al. reported in the literature "Nature, 2009, 461 (7261): 246-249" that a multi-stage hole nanosheet ZSM-5 molecular sieve was synthesized by one-step hydrothermal synthesis with Gemini quaternary ammonium salt surfactant C 22 H 45 -N + (CH3)2-C6H 12 -N + (CH3)2-C6H 13 (referred to as C 22-6-6 ) as a template, wherein the thickness of the nanosheet is only about 2 nm. This innovative research provides a new direction for the application of molecular sieve in adsorption, separation and catalysis, etc. At the same time, it has triggered a hot wave of research and application research based on the morphology structure synthesis of nanosheet molecular sieve, and many research progress has been made.

[0004] The literature Chemistry of Materials, 2011, 23 (5): 1273-1279 discloses the following: a Gemini quaternary ammonium salt surfactant C 22 H 45 -N + (CH3)2-C6H 12 -N + (CH3)2-C6H 13 (C 22 -N2-C6) was designed to have a unique structure of amphiphilic surfactant C 22 -N2-C6Br2, which was mixed uniformly with a silicate sol-gel, and an ordered MFI zeolite nanosheet with a single layer of 2 nm thickness was synthesized by hydrothermal crystallization at 150℃ for 3 days, and the BET specific surface area and pore volume values thereof were as high as 660 m 2 g -1and 1.1 cm 3 g -1 .

[0005] The document Chemistry of Materials, 2014, 26(3): 1345-1355 discloses the following: Using tetrapropylammonium hydroxide (TPAOH) as a microporous template, a gemini quaternary ammonium surfactant C 22-6-6 was prepared as a second template to prepare nanosheet molecular sieves with hierarchical pore structure. With the continuous addition of TPAOH, the morphology, mesoporous structure and catalytic activity in the catalytic conversion of benzene methanol in mesitylene of the obtained MFI nanosheet have corresponding synchronous changes.

[0006] The document Microporous and Mesoporous Materials, 2017, 237: 90-107 discloses the following: Using bifunctional templates [C6H 13 -N + (CH3)2-C6H 12 -N + (CH3)2-C6H 13 ](Br - )2 and [C8H 17 -N + (CH3)2-C6H 12 -N + (CH3)2-C8H 17 ](Br - )2, two nanosheet ZSM-5 molecular sieves with different morphologies were synthesized. Compared with conventional ZSM-5 molecular sieves, the two molecular sieves have more accessible active centers and larger specific surface area, and the catalytic effect in macromolecular reactions is significantly improved.

[0007] The document Chemistry of Materials, 2014, 26(24): 7183-7188 discloses the following: By introducing three branched quaternary ammonium head groups on the benzene ring, Ph-(O-C 10 H 20 -N + (Me)2-C6H 12 -N + (Me)2-C6H 13 ·2Br - )3 cationic template (TC Ph-10-6-6 ) was finally synthesized. The growth of the molecular sieve along the a and c axes has been affected by TC Ph-10-6-6The restriction of three hydrophobic alkyl chains of the Gemini quaternary ammonium salt surfactant forms rich crystal surfaces in the cross-linking of the three axes of the a-axis, the b-axis and the c-axis, and finally obtains single crystal MFI nanosheet (SCMZ). The three-dimensional coupled cross-linking structure is relatively stable, and the nanosheet structure will not collapse due to calcination. Compared with the conventional ZSM-5 molecular sieve, the SCMZ has higher catalytic activity and excellent selectivity in the catalytic reaction of macromolecules and micromolecules.

[0008] The synthesis process of the Gemini quaternary ammonium salt surfactant required for synthesizing the nanosheet molecular sieve in the above document is complicated, and the raw material price is extremely high, so large-scale production cannot be realized, and the application of the nanosheet molecular sieve in industrial catalysis is also restricted.

[0009] The document Microporous and Mesoporous Materials, 2018, 270: 57-66 discloses the following: by introducing glucose into the ZSM-5 molecular sieve synthesis system, using its inhibition effect on crystal growth, large prismatic nanosheet ZSM-5 crystals are synthesized, which reduces the b-axis length of the ZSM-5 molecular sieve and forms a nanosheet structure, but the mesopore specific surface area of the molecular sieve is still small, and the pore structure of the catalyst cannot be guaranteed, and it is not easy to produce on a large scale.

[0010] The document Industrial & Engineering Chemistry Research, 2019, 58, 12611-12622 discloses the following: by using urea as an additive, a ZSM-5 molecular sieve with a b-axis length of 60 nm is synthesized, which has a nanometer straight channel along the b-axis and moderate acidity, and compared with the conventional ZSM-5 molecular sieve, it has higher propyl aldehyde conversion rate, stability and selectivity due to the ability to fully access the active acid site and rapidly diffuse through the nanometer channel. However, the mesopore volume of the molecular sieve is relatively small, and the use of urea as an additive will produce wastewater, which is easy to affect the environment. SUMMARY

[0011] The purpose of the present application is to provide a synthesis method of a hierarchical pore nanosheet structure ZSM-5 molecular sieve, to solve the problems of small specific surface area and mesopore volume of the nanosheet structure ZSM-5 molecular sieve in the prior art, and the complicated preparation process.

[0012] To achieve the above-mentioned purpose, the present application provides a synthesis method of a hierarchical pore nanosheet structure ZSM-5 molecular sieve, comprising the following steps:

[0013] S1, mixing, stirring a silicon source, an alkali source, an aluminum source, a micropore template agent and water to form a ZSM-5 molecular sieve precursor gel;

[0014] S2, adding a mesopore template agent and a crystal growth inhibitor into the ZSM-5 molecular sieve precursor gel, then performing a crystallization reaction, and after the reaction is completed, the product is filtered, washed, dried, and calcined to obtain the ZSM-5 molecular sieve with a hierarchical pore flake structure.

[0015] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the molar ratio of the alkali source (calculated as Na2O), the aluminum source (calculated as Al2O3), the silicon source (calculated as SiO2), the micropore template agent, water, the mesopore template agent, and the crystal growth inhibitor is 1-20:1:10-220:3.25-11:10-4000:1-2.2:1-10.

[0016] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the alkali source is one or more of sodium hydroxide, sodium oxide, and water glass.

[0017] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the aluminum source is one or more of sodium aluminate, aluminum sulfate, aluminum chloride, aluminum nitrate, and aluminum isopropyl alcohol.

[0018] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the alkali source is one or more of sodium hydroxide, sodium oxide, and water glass.

[0019] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the micropore template agent is one or more of tetrapropylammonium bromide TPABr, tetrapropylammonium hydroxide TPAOH, tetramethylammonium hydroxide, and butylamine, and preferably tetrapropylammonium bromide and / or tetrapropylammonium hydroxide.

[0020] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the mesopore template agent is an amphiphilic organosilane surfactant, and preferably octadecyl dimethyl trimethoxysilyl propyl ammonium chloride TPOAC and / or hexadecyl dimethyl trimethoxysilyl propyl ammonium chloride TPHAC.

[0021] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the crystal growth inhibitor is one or more of glucose, fructose, maltose, and sucrose.

[0022] The synthesis method of the ZSM-5 molecular sieve with a hierarchical pore flake structure has the following characteristics: the crystallization temperature is 50-300 DEG C, and preferably 130-160 DEG C; and the crystallization time is 12-72 h, and preferably 24-48 h.

[0023] The synthesis method of the hierarchical thin slice structure ZSM-5 molecular sieve, the crystallinity of the molecular sieve is greater than 80%, the specific surface area of the mesopore is 120-200 m 2 / g, and the b-axis length is 100-200 nm.

[0024] The present application has the following advantages:

[0025] The present application directly synthesizes the hierarchical thin slice structure ZSM-5 molecular sieve by using a hydrothermal synthesis method, controls the product to form a thin slice structure by introducing glucose into the system, introduces an amphiphilic organosilane surfactant as a mesopore template agent, forms a homogeneous gel by mixing the micelles formed by the self-assembly of the silicon-aluminum species, removes the mesopore by calcining at high temperature after crystallization, the b-axis length of the product is 100-200 nm, the external specific surface area is greater than 120 m 2 / g, can effectively promote the diffusion and mass transfer of macromolecular reactants and products, has good thermal stability and hydrothermal stability, and good catalyst activity accessibility. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A scanning electron microscope (SEM) photo of the hierarchical thin slice structure ZSM-5 molecular sieve product prepared in Example 1;

[0027] Figure 2 An X-ray diffraction (XRD) spectrum of the hierarchical thin slice structure ZSM-5 molecular sieve prepared in Example 1. DETAILED DESCRIPTION

[0028] The present application will be described in detail by the following examples. It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content of the present application.

[0029] Raw material sources: aluminum sulfate and other raw materials from China Petroleum Lanzhou Petrochemical Company, all are industrial products; micropore template agent is purchased from Anhui Jin'ao Chemical Co., Ltd., is an industrial product, tetraethyl orthosilicate, white carbon black, kaolin, mesopore template agent and crystal growth inhibitor are all commercially available reagents, and are industrial grade.

[0030] Analysis method: phase detection and confirmation is carried out by using an XRD-7000 type X-ray crystal powder diffractometer of Shimadzu Corporation, Japan. Instrument parameters: Cu-Ka ray, wavelength is 0.1543 nm, tube voltage is 40 kV, and tube current is 30 mA. Sample testing conditions: scanning angle is 5°-40°, and scanning speed is 6° / min.

[0031] The sample morphology was observed using a HITACHI S-4700 scanning electron microscope. The instrument parameters were: cold field emission electron gun, acceleration voltage of 0.5-30 kV.

[0032] An ASAP2020M full-automatic adsorption instrument produced by the American Micromeritics company was used to measure the adsorption and desorption isotherms of the sample at liquid nitrogen temperature, nitrogen was used as the adsorbate, the specific surface area of the sample was calculated according to the adsorption equilibrium isotherm between the relative pressure of 0.05-0.25 by using the Brunauer-Emmett-Teller (BET) equation, the internal surface area and the external surface area of the sample were distinguished by using the t-plot model, the pore volume and the pore size distribution were measured by using the static capacity method, so as to calculate the pore structure parameters.

[0033] Example 1

[0034] The present embodiment provides a preparation method of a hierarchical thin sheet structure ZSM-5 molecular sieve, and the molar ratio of the alkali source, the aluminum source, the silicon source, the micropore template agent, the water, the mesopore template agent and the crystal growth inhibitor is 1:1:10:3.25:10:1:1. The method comprises the following steps:

[0035] At room temperature, 0.5 g of water glass, 0.3 g of silicon powder and 0.66 g of TPABr template agent were dissolved in 4.81 g of deionized water and stirred uniformly; 0.5 g of aluminum sulfate octadecahydrate was dissolved in 5 g of water and placed in a 25 mL beaker, which was stirred by a magnetic stirrer, and after complete dissolution, the above two solutions were mixed to form a silica-alumina gel, and the gel was obtained after 2 h of continuous vigorous stirring and aging; 0.1 g of the crystal growth inhibitor glucose and 0.7 g of the mesopore template agent TPHAC were sequentially added to the gel; the gel was transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature was 50°C, the crystallization time was 72 h, and after the crystallization was completed, the obtained solid product was subjected to suction filtration, washing and drying;

[0036] The above dried solid product was placed in a muffle furnace for calcination at a temperature of 550°C, and the calcination time was 8 h, and after removing the organic template agent therefrom, a sodium type hierarchical thin sheet structure ZSM-5 molecular sieve was obtained.

[0037] The prepared molecular sieve was subjected to phase detection, Figure 1 is an SEM photograph, Figure 2 is an XRD pattern, it can be seen that: the synthetic sample is a pure phase ZSM-5 molecular sieve, and the morphology is a thin sheet.

[0038] Example 2

[0039] The embodiment provides a preparation method of a multi-level hole thin piece structure ZSM-5 molecular sieve, and molar ratios of an alkali source, an aluminum source, a silicon source, a micropore template agent, water, a mesopore template agent and a crystal growth inhibitor are 20:1:220:11:4000:2.2:2.2. The method comprises the following steps:

[0040] At room temperature, 10.3g water glass, 7.0g silicon powder and 2.2g TPABr template agent are dissolved in 37g deionized water and stirred uniformly; 0.3g aluminum isopropoxide is dissolved in 10g water and placed in a 25mL beaker, and stirring is performed by using a magnetic stirrer; after complete dissolution, the two solutions are mixed to form a silicon-aluminum gel, and the gel is continuously stirred and aged for 2h to obtain a gel; 0.3g crystal growth inhibitor glucose and 1.5g mesopore template agent TPHAC are sequentially added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 300 DEG C, the crystallization time is 12h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0041] The dried solid product is placed in a muffle furnace for calcination at a temperature of 550 DEG C, the calcination time is 8h, and after the organic template agent is removed, a sodium type multi-level hole thin piece structure ZSM-5 molecular sieve is obtained.

[0042] Embodiment 3

[0043] The embodiment provides a preparation method of a multi-level hole thin piece structure ZSM-5 molecular sieve, and molar ratios of an alkali source, an aluminum source, a silicon source, a micropore template agent, water, a mesopore template agent and a crystal growth inhibitor are 10:1:110:5.5:2000:1.1:1.1. The method comprises the following steps:

[0044] At room temperature, 5.1g water glass, 3.9g white carbon black and 3.3g TPAOH template agent are dissolved in 14g deionized water and stirred uniformly; 1.2g aluminum isopropoxide is dissolved in 10g water and placed in a 25mL beaker, and stirring is performed by using a magnetic stirrer; after complete dissolution, the two solutions are mixed to form a silicon-aluminum gel, and the gel is continuously stirred and aged for 2h to obtain a gel; 0.15g crystal growth inhibitor fructose and 0.81g mesopore template agent TPOAC are sequentially added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 150 DEG C, the crystallization time is 36h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0045] The dried solid product is placed in a muffle furnace for calcination at a temperature of 550 DEG C, the calcination time is 8h, and after the organic template agent is removed, a sodium type multi-level hole thin piece structure ZSM-5 molecular sieve is obtained.

[0046] Embodiment 4

[0047] The embodiment provides a preparation method of a multi-level hole thin piece structure ZSM-5 molecular sieve, and the molar ratio of an alkali source, an aluminum source, a silicon source, a micropore template agent, water, a mesopore template agent and a crystal growth inhibitor is 8:1:100:5:1800:1:10. The method comprises the following steps:

[0048] At room temperature, 5.2g of tetraethyl orthosilicate and 0.9g of a tetramethyl ammonium hydroxide template agent are dissolved in 8.2g of deionized water and stirred uniformly; 0.1g of sodium aluminate and 0.3g of sodium hydroxide are dissolved in 8g of water and placed in a 25mL beaker, and stirring is performed by using a magnetic stirrer, and after complete dissolution, the two kinds of solutions are mixed to form a silicon aluminum gel, and the stirring is continuously performed, and the gel is obtained after aging for 2h; 0.9g of a crystal growth inhibitor maltose and 0.5g of a mesopore template agent TPHAC are sequentially added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 170 DEG C, the crystallization time is 48h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0049] The dried solid product is placed in a muffle furnace for calcination at a temperature of 550 DEG C, the calcination time is 8h, and after the organic template agent is removed, a sodium type multi-level hole thin piece structure ZSM-5 molecular sieve is obtained.

[0050] Embodiment 5

[0051] The embodiment provides a preparation method of a multi-level hole thin piece structure ZSM-5 molecular sieve, and the molar ratio of an alkali source, an aluminum source, a silicon source, a micropore template agent, water, a mesopore template agent and a crystal growth inhibitor is 12:1:100:5:2000:2:5. The method comprises the following steps:

[0052] At room temperature, 8.7g of tetraethyl orthosilicate and 0.3g of butylamine template agent are dissolved in 20g of deionized water and stirred uniformly; 0.2g of aluminum chloride and 0.6g of sodium oxide are dissolved in 10g of water and placed in a 25mL beaker, and stirring is performed by using a magnetic stirrer, and after complete dissolution, the two kinds of solutions are mixed to form a silicon aluminum gel, and the stirring is continuously performed, and the gel is obtained after aging for 2h; 0.8g of a crystal growth inhibitor glucose and 1.6g of a mesopore template agent TPHAC are sequentially added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 170 DEG C, the crystallization time is 24h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0053] The dried solid product is placed in a muffle furnace for calcination at a temperature of 550 DEG C, the calcination time is 8h, and after the organic template agent is removed, a sodium type multi-level hole thin piece structure ZSM-5 molecular sieve is obtained.

[0054] Example 6

[0055] The present example provides a preparation method of a hierarchical thin sheet structure ZSM-5 molecular sieve, the molar ratio of the alkali source, the aluminum source, the silicon source, the micropore template agent, water, the mesopore template agent and the crystal growth inhibitor is 12:1:100:5:2000:2:5. The method comprises the following steps:

[0056] At room temperature, 5.0 g of silicon powder and 1.1 g of TPABr template agent are dissolved in 20 g of deionized water and stirred uniformly; 0.6 g of aluminum nitrate and 0.6 g of sodium oxide are dissolved in 10 g of water and placed in a 25 mL beaker, stirred with a magnetic stirrer, and after complete dissolution, the above two solutions are mixed to form a silicon-aluminum gel, and the gel is obtained after 2 h of continuous vigorous stirring and aging; 0.8 g of crystal growth inhibitor fructose and 1.6 g of mesopore template agent TPHAC are added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 170°C, the crystallization time is 24 h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0057] The above dried solid product is placed in a muffle furnace for calcination at a temperature of 550°C, the calcination time is 8 h, and after removing the organic template agent therein, a sodium type hierarchical thin sheet structure ZSM-5 molecular sieve is obtained.

[0058] Example 7

[0059] The present example provides a preparation method of a hierarchical thin sheet structure ZSM-5 molecular sieve, the molar ratio of the alkali source, the aluminum source, the silicon source, the micropore template agent, water, the mesopore template agent and the crystal growth inhibitor is 12:1:100:5:2000:2:5. The method comprises the following steps:

[0060] At room temperature, 5.0 g of silicon powder and 1.1 g of TPABr template agent are dissolved in 20 g of deionized water and stirred uniformly; 0.6 g of aluminum nitrate and 0.6 g of sodium oxide are dissolved in 10 g of water and placed in a 25 mL beaker, stirred with a magnetic stirrer, and after complete dissolution, the above two solutions are mixed to form a silicon-aluminum gel, and the gel is obtained after 2 h of continuous vigorous stirring and aging; 0.8 g of crystal growth inhibitor fructose and 1.6 g of mesopore template agent TPHAC are added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 170°C, the crystallization time is 24 h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0061] The above dried solid product is placed in a muffle furnace for calcination at a temperature of 550°C, the calcination time is 8 h, and after removing the organic template agent therein, a sodium type hierarchical thin sheet structure ZSM-5 molecular sieve is obtained.

[0062] Comparative Example 1

[0063] The present comparative example provides a preparation method of a conventional microporous ZSM-5 zeolite, which comprises the following steps:

[0064] At room temperature, 0.41 g of potassium hydroxide, 0.11 g of sodium hydroxide and 20 g of tetrapropylammonium bromide template were dissolved in 20 g of deionized water and stirred uniformly; 0.25 g of aluminum hydroxide was added and continued to be stirred until dissolved; 25 g of Ludox AS40 (40%) was added and continued to be stirred vigorously, and a gel was obtained after aging for 2 h;

[0065] The gel was transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature was 170°C, the crystallization time was 7 d, and after the crystallization was completed, the obtained solid product was subjected to suction filtration, washing and drying;

[0066] The above dried solid product was placed in a muffle furnace for calcination at a temperature of 550°C, the calcination time was 8 h, and after removing the organic template SDA therein, a sodium type conventional microporous ZSM-5 molecular sieve was obtained.

[0067] Comparative Example 2

[0068] The present comparative example provides a preparation method of a hierarchical pore ZSM-5 molecular sieve with only mesoporous no flake structure introduced, the molar ratio of alkali source, aluminum source, silicon source, microporous template, water and mesoporous template is 12:1:100:5:2000:1. It comprises the following steps:

[0069] At room temperature, 6.2 g of water glass, 2.8 g of silicon powder and 1.0 g of TPABr template were dissolved in 13 g of deionized water and stirred uniformly; 0.5 g of aluminum sulfate octadecahydrate was dissolved in 10 g of water and placed in a 25 mL beaker, stirred with a magnetic stirrer, and after complete dissolution, the above two solutions were mixed to form a silica-alumina gel, and continued to be stirred vigorously, and a gel was obtained after aging for 2 h; 0.7 g of mesoporous template TPHAC was added to the above gel; the gel was transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature was 170°C, the crystallization time was 24 h, and after the crystallization was completed, the obtained solid product was subjected to suction filtration, washing and drying;

[0070] The above dried solid product was placed in a muffle furnace for calcination at a temperature of 550°C, the calcination time was 8 h, and after removing the organic template therein, a sodium type hierarchical pore ZSM-5 molecular sieve was obtained.

[0071] Comparative Example 3

[0072] The comparative example provides a preparation method of a microporous ZSM-5 molecular sieve only introducing a sheet structure, and the molar ratio of the alkali source, the aluminum source, the silicon source, the microporous template agent, water and the crystal growth inhibitor is 12:1:100:5:2000:10. The method comprises the following steps:

[0073] At room temperature, 6.2 g of water glass, 2.8 g of silicon powder and 1.0 g of TPABr template agent are dissolved in 13 g of deionized water and stirred uniformly; 0.5 g of aluminum sulfate octadecahydrate is dissolved in 10 g of water and placed in a 25 mL beaker, stirred with a magnetic stirrer, and after complete dissolution, the two solutions are mixed to form a silica-aluminum gel, and the stirring is continued, and the gel is obtained after aging for 2 h; 1.3 g of crystal growth inhibitor glucose is added to the gel; the gel is transferred to a polytetrafluoroethylene-lined crystallization kettle for hydrothermal crystallization treatment, the crystallization temperature is 170 DEG C, the crystallization time is 24 h, and after the crystallization is completed, the obtained solid product is subjected to suction filtration, washing and drying;

[0074] The above dried solid product is placed in a muffle furnace for calcination at a temperature of 550 DEG C, and the calcination time is 8 h, and after removing the organic template agent therein, a sodium type sheet structure ZSM-5 molecular sieve is obtained.

[0075] Table 1 Comparison of pore structure parameters of the sample of the example and the comparative example

[0076]

[0077] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for synthesizing a hierarchical-pore thin sheet structure ZSM-5 molecular sieve, characterized in that, The method comprises the following steps: S1, mixing, stirring a silicon source, an alkali source, an aluminum source, a microporous template agent and water to form a ZSM-5 molecular sieve precursor gel; S2, adding a mesoporous template agent and a crystal growth inhibitor to the ZSM-5 molecular sieve precursor gel, then performing a crystallization reaction, and after the reaction is completed, the product is filtered, washed, dried and calcined to obtain a hierarchical pore thin sheet structure ZSM-5 molecular sieve; The mesoporous template agent is octadecyl dimethyl trimethoxysilyl propyl ammonium chloride TPOAC and / or hexadecyl dimethyl trimethoxysilyl propyl ammonium chloride TPHAC. The crystal growth inhibitor is one or more of glucose, fructose, maltose and sucrose. The molecular sieve has a crystallinity of greater than 80 %, a specific surface area of mesopores of 120-200 m 2 / g, and a b-axis length of 100-200 nm.

2. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, characterized in that, The molar ratio of the alkali source (calculated as Na2O), the aluminum source (calculated as Al2O3), the silicon source (calculated as SiO2), the microporous template agent, water, the mesoporous template agent and the crystal growth inhibitor is 1-20:1:10-220:3.25-11:10-4000:1-2.2:1-10.

3. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, characterized in that, The silicon source is one or more of tetraethyl orthosilicate, white carbon black, water glass, and silicon powder.

4. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, wherein, The aluminum source is one or more of sodium aluminate, aluminum sulfate, aluminum chloride, aluminum nitrate, and aluminum isopropyl alcohol.

5. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, wherein, The alkali source is one or more of water glass, sodium hydroxide, and sodium oxide.

6. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, wherein, The microporous template agent is one or more of tetrapropyl ammonium bromide TPABr, tetrapropyl ammonium hydroxide TPAOH, tetramethyl ammonium hydroxide, and butylamine.

7. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, wherein, The microporous template agent is tetrapropyl ammonium bromide and / or tetrapropyl ammonium hydroxide.

8. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, wherein, The crystallization temperature is 50-300 °C, and the crystallization time is 12-72 h.

9. The method of synthesizing a hierarchical pore sheet structure ZSM-5 molecular sieve according to claim 1, wherein, The crystallization temperature is 130-160 °C, and the crystallization time is 24-48 h.

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