阅读说明：本技术 一种多级孔zsm-5纳米沸石的制备方法 (Preparation method of hierarchical porous ZSM-5 nano zeolite ) 是由 勾明雷 段永华 郭亚菲 刘振 宋文生 于 2020-12-17 设计创作，主要内容包括：本发明公开了一种多级孔ZSM-5纳米沸石的制备方法,该制备方法包括如下步骤：先将硅源、结构导向剂和去离子水混合均匀,在室温下搅拌10~12h,然后转移至聚四氟反应釜中,在100~150℃下处理24h；然后将硅源、铝源和去离子水搅拌均匀,加入晶种导向胶,在室温下搅拌2~5h,然后将混合物移至烘箱中于70~90℃干燥12~24h得到干凝胶,将干凝胶置于聚四氟反应釜的小衬中,小衬置于聚四氟反应釜的大衬中,向大衬底部加入1.0~2.0mL的去离子水,将聚四氟反应釜置于120~180℃温度下反应一段时间,然后取出急冷,再经干燥、煅烧,即得到多级孔ZSM-5纳米沸石。本发明的制备方法能够直接将纳米沸石粒子组装为多级孔结构的ZSM-5纳米沸石,具有结晶速度快、原料转化率高、生产成本低、无废液污染等优点。(The invention discloses a preparation method of hierarchical pore ZSM-5 nano zeolite, which comprises the following steps: uniformly mixing a silicon source, a structure directing agent and deionized water, stirring at room temperature for 10-12 hours, transferring to a polytetrafluoroethylene reaction kettle, and treating at 100-150 ℃ for 24 hours; and then uniformly stirring a silicon source, an aluminum source and deionized water, adding a crystal seed guide adhesive, stirring for 2-5 h at room temperature, then transferring the mixture into an oven, drying at 70-90 ℃ for 12-24 h to obtain dry gel, placing the dry gel into a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner into a large liner of the polytetrafluoroethylene reaction kettle, adding 1.0-2.0 mL of deionized water into the large substrate, placing the polytetrafluoroethylene reaction kettle at 120-180 ℃ for reaction for a period of time, taking out the polytetrafluoroethylene reaction kettle for quenching, drying and calcining to obtain the hierarchical pore ZSM-5 nano zeolite. The preparation method can directly assemble the nano zeolite particles into the ZSM-5 nano zeolite with the hierarchical pore structure, and has the advantages of high crystallization speed, high raw material conversion rate, low production cost, no waste liquid pollution and the like.)

1. A preparation method of hierarchical porous ZSM-5 nano zeolite is characterized by comprising the following steps:

(1) preparing seed crystal guide glue: and (2) mixing a silicon source, a structure directing agent and deionized water according to the weight ratio of (0.25-0.55): 1: (10-30), stirring for 10-12 h at room temperature, transferring to a polytetrafluoroethylene reaction kettle, and treating for 24h at 100-150 ℃;

(2) preparing hierarchical porous ZSM-5 nano zeolite: mixing a silicon source, an aluminum source and deionized water according to the weight ratio of 1: (0-0.1): (10-30), adding the seed crystal guide glue prepared in the step (1), stirring at room temperature for 2-5 hours, transferring the mixture into an oven, drying at 70-90 ℃ for 12-24 hours to obtain dry gel, placing the dry gel into a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner into a large liner of the polytetrafluoroethylene reaction kettle, adding 1.0-2.0 mL of deionized water into the large liner, placing the polytetrafluoroethylene reaction kettle at 120-180 ℃ for reaction for a period of time, taking out, quenching, drying and calcining to obtain the hierarchical pore ZSM-5 nano zeolite.

2. The method for preparing hierarchical pore ZSM-5 nano zeolite of claim 1, wherein: in the step (2), after quenching, drying is carried out at the temperature of 120-200 ℃ for 4-10 h; the calcination temperature is 450-550 ℃, and the calcination time is 4-10 h.

3. The method for preparing hierarchical pore ZSM-5 nano zeolite of claim 1, wherein: in the step (2), the polytetrafluoroethylene reaction kettle is placed at the temperature of 120-180 ℃ for reaction for 24-120 h.

4. The method for preparing a hierarchical pore ZSM-5 nano zeolite according to claim 3, wherein: in the step (2), the polytetrafluoroethylene reaction kettle is placed at the temperature of 120-180 ℃ for reaction for 72-96 hours.

5. The method for preparing hierarchical pore ZSM-5 nano zeolite of claim 1, wherein: in the step (2), SiO contained in the seed crystal guiding glue is added₂The amount of the SiO in the silicon source added in the step (2)₂2.5-25 wt% of the total weight of the composition.

6. The method for preparing a hierarchical pore ZSM-5 nano zeolite according to claim 5, wherein: in the step (2), SiO contained in the seed crystal guiding glue is added₂The SiO in the silicon source added in the step (2)₂10-20 wt% of the content.

7. The method for preparing hierarchical pore ZSM-5 nano zeolite of claim 1, wherein: the silicon source is at least one of tetraethyl silicate, tetramethyl silicate, silica gel, water glass and sodium silicate.

8. The method for preparing hierarchical pore ZSM-5 nano zeolite of claim 1, wherein: the aluminum source is at least one of aluminum sulfate, pseudo-boehmite and sodium metaaluminate.

9. The method for preparing hierarchical pore ZSM-5 nano zeolite of claim 1, wherein: the structure directing agent is at least one of tetrapropylammonium hydroxide and tetrapropylammonium bromide.

Technical Field

The invention relates to the technical field of zeolite molecular sieve materials, in particular to a preparation method of hierarchical porous ZSM nano zeolite.

Background

The nano zeolite has larger external specific surface area, shorter transmission distance and abundant surface silicon hydroxyl, and has unique advantages in the fields of catalytic reaction, ion exchange, gas adsorption and the like, such as improvement of the utilization rate of zeolite, enhancement of the transmission capability of macromolecules, reduction of deep reaction of products, reduction of carbon deposition inactivation rate and improvement of selectivity. However, the nano zeolite is difficult to separate and is easy to generate disordered aggregation, and the full utilization of the pore channel and the outer surface of the nano zeolite is severely limited. The nano zeolite is assembled into a macroscopic zeolite crystal with a specific morphology and a hierarchical pore structure, and mesoporous channels between crystals or in the crystal are used as a transmission channel of guest molecules, so that the advantages of the nano zeolite can be fully exerted, and the problem that the nano zeolite is difficult to separate is solved.

The mesoporous molecular sieve material can be obtained by adopting a multi-step method to mix a precursor containing zeolite seed crystals with a mesoporous template agent or dipping the precursor containing the zeolite seed crystals on the walls of mesoporous pores and continuously crystallizing under a hydrothermal condition, but the walls of the mesoporous pores are of a pseudo zeolite structure, have no long-range order and have poorer hydrothermal stability and acidity compared with zeolite crystals. Ordered mesoporous carbon is taken as a template agent, a zeolite precursor is crystallized in a mesoporous duct of the carbon template agent, and mesoporous ZSM-5 zeolite can be obtained after the template agent is removed. However, in this method, the carbon template is incompatible with the zeolite precursor solution, the production cost is high, and in addition, the process of removing the carbon template can cause certain damage to the channel structure. Some macromolecular organic amines with special structures have the guiding capability of micropore and mesoporous structures, can avoid the problem of phase separation, can directly synthesize mesoporous ZSM-5 zeolite through hydrothermal reaction, and the mesoporous wall is composed of nano zeolite crystals. Most of the quaternary ammonium salt surfactants are not commercialized, the preparation steps are complex, and the micropore and mesoporous structures in the synthesized mesoporous zeolite are difficult to have long-range order at the same time.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides a preparation method of hierarchical pore ZSM nano zeolite, which has mild crystallization conditions, small using amount of a structure directing agent and no need of separating the nano zeolite, and can directly assemble the nano zeolite into ZSM-5 nano zeolite with a hierarchical pore structure.

In order to achieve the purpose, the invention adopts the specific scheme that:

a preparation method of hierarchical pore ZSM-5 nano zeolite comprises the following steps:

(1) preparing seed crystal guide glue: and (2) mixing a silicon source, a structure directing agent and deionized water according to the weight ratio of (0.25-0.55): 1: (10-30), stirring for 10-12 h at room temperature, transferring to a polytetrafluoroethylene reaction kettle, and treating for 24h at 100-150 ℃;

(2) and preparing the hierarchical pore ZSM-5 nano zeolite: mixing a silicon source, an aluminum source and deionized water according to the weight ratio of 1: (0-0.1): (10-30), adding the seed crystal guide glue prepared in the step (1), stirring at room temperature for 2-5 hours, transferring the mixture into an oven, drying at 70-90 ℃ for 12-24 hours to obtain dry gel, placing the dry gel into a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner into a large liner of the polytetrafluoroethylene reaction kettle, adding 1.0-2.0 mL of deionized water into the large liner, placing the polytetrafluoroethylene reaction kettle at 120-180 ℃ for reaction for a period of time, taking out, quenching, drying and calcining to obtain the hierarchical pore ZSM-5 nano zeolite.

Further, in the step (2), the temperature of the molding drying after quenching is 120-200 ℃, and the drying time is 4-10 h; the calcination temperature is 450-550 ℃, and the calcination time is 4-10 h.

Further, in the step (2), the polytetrafluoroethylene reaction kettle is placed at the temperature of 120-180 ℃ for reaction for 24-120 h.

Further, in the step (2), the polytetrafluoroethylene reaction kettle is placed at the temperature of 120-180 ℃ for reaction for 72-96 hours.

Further, in the step (2), SiO contained in the seed crystal guiding glue is added₂The amount of the SiO in the silicon source added in the step (2)₂2.5-25 wt% of the total weight of the composition.

Further, in the step (2), seed crystals are addedSiO contained in the guiding glue₂SiO in the silicon source in the step (2)₂10-20 wt% of the content.

Further, the silicon source is at least one of tetraethyl silicate, tetramethyl silicate, silica gel, water glass and sodium silicate.

Further, the aluminum source is at least one of aluminum sulfate, pseudo-boehmite and sodium metaaluminate.

Further, the structure directing agent is at least one of tetrapropylammonium hydroxide and tetrapropylammonium bromide.

Has the advantages that:

1. the dosage of the structure directing agent is only less than 20 percent of the dosage of the common hydrothermal reaction, no aqueous solution participates in the crystallization process of the nano zeolite, and the silicon-aluminum gel is directly crystallized on the surface of the seed crystal to form the ZSM-5 nano zeolite with the hierarchical pore structure without separation.

2. The preparation method can directly assemble the nano zeolite particles into the ZSM-5 nano zeolite with the hierarchical pore structure, and has the advantages of high crystallization speed, high raw material conversion rate, low production cost, no waste liquid pollution and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

Fig. 1 is an XRD pattern of nano zeolite prepared in examples 1 to 3 of the present invention.

Fig. 2 is an SEM image of the seed-guiding glue.

Fig. 3 is an SEM image of the nano zeolite prepared in example 1.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.

A preparation method of hierarchical pore ZSM-5 nano zeolite comprises the following steps:

(1) preparing seed crystal guide glue: and (2) mixing a silicon source, a structure directing agent and deionized water according to the weight ratio of (0.25-0.55): 1: (10-30), stirring for 10-12 h at room temperature, transferring to a polytetrafluoroethylene reaction kettle, and treating for 24h at 100-150 ℃;

(2) and preparing the hierarchical pore ZSM-5 nano zeolite: mixing a silicon source, an aluminum source and deionized water according to the weight ratio of 1: (0-0.1): (10-30), adding the seed crystal guide glue prepared in the step (1), stirring at room temperature for 2-5 hours, transferring the mixture to an oven, drying at 70-90 ℃ for 12-24 hours to obtain dried gel, placing the dried gel in a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner in a large liner of the polytetrafluoroethylene reaction kettle, adding 1.0-2.0 mL of deionized water to the large liner to ensure that the deionized water is not in contact with the dried gel, and placing the polytetrafluoroethylene reaction kettle at 120-180 ℃ for reaction for 24-120 hours, preferably 72-96 hours; taking out, quenching, drying and calcining, wherein the drying temperature is 120-200 ℃, and the drying time is 4-10 hours; and calcining at the temperature of 450-550 ℃ for 4-10 hours to obtain the hierarchical-pore ZSM-5 nano zeolite.

In the step (2), SiO contained in the seed crystal guiding glue is added₂The amount of the SiO in the silicon source added in the step (2)₂2.5 to 25wt%, preferably 10 to 20 wt%.

Wherein the silicon source is at least one of tetraethyl silicate, tetramethyl silicate, silica gel, water glass and sodium silicate. The aluminum source is at least one of aluminum sulfate, pseudo-boehmite and sodium metaaluminate. The structure directing agent is at least one of tetrapropylammonium hydroxide and tetrapropylammonium bromide.

Example 1

(1) Preparing seed crystal guide glue: uniformly mixing a tetraethyl silicate silicon source, tetrapropylammonium hydroxide and deionized water according to a molar ratio of 0.35:1:1:20, stirring at room temperature for 12 hours, transferring to a polytetrafluoroethylene reaction kettle, and treating at 100 ℃ for 24 hours;

(2) preparing hierarchical pore ZSM-5 nano zeolite: uniformly stirring silica gel, aluminum sulfate and deionized water according to the molar ratio of 1:0.01:20, and adding the contained SiO₂The SiO in the silicon source added in the step (2)₂The seed crystal guide glue with the content of 10 wt% is stirred for 2 hours at room temperature; then transferring the mixture into an oven at 70 ℃ for drying for 12 h; placing the dried gel in a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner in a large liner of the polytetrafluoroethylene reaction kettle, and adding 1.0mL of deionized water into the large liner to ensure that the deionized water is not in contact with the dried gel; taking out the reaction kettle after reacting for 72 hours at 120 ℃, and quenching; and drying at 120 ℃ for 5h and calcining at 550 ℃ for 6h to obtain the hierarchical pore ZSM-5 nano zeolite which is marked as sample 1, wherein the sample 1 simultaneously contains micropores and mesopores.

The SEM images of the seed-guiding gel and sample 1 are shown in detail in fig. 2 and 3, respectively, and it can be seen from fig. 2 and 3 that the seed-guiding gel contains a large amount of spherical nano-zeolite particles having a particle size of about 100 nm. Sample 1 is amorphous silica-alumina gel nano zeolite particles with the size of 300-400 nm and rapidly grown on the surface of the seed crystal, and a certain mesoporous pore channel is formed among the nano particles.

Example 2

(1) Preparing seed crystal guide glue: uniformly mixing a tetraethyl silicate silicon source, tetrapropylammonium hydroxide and deionized water according to a molar ratio of 0.35:1:1:20, stirring at room temperature for 12 hours, transferring to a polytetrafluoroethylene reaction kettle, and treating at 100 ℃ for 24 hours;

(2) preparing hierarchical pore ZSM-5 nano zeolite: uniformly stirring silica gel, aluminum sulfate and deionized water according to the molar ratio of 1:0.01:20, and adding the contained SiO₂The SiO in the silicon source added in the step (2)₂Seed crystal guide glue with the content of 15 wt% is stirred for 2 hours at room temperature; then transferring the mixture into an oven at 70 ℃ for drying for 12 h; placing the dried gel in a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner in a large liner of the polytetrafluoroethylene reaction kettle, and adding 1.0mL of deionized water into the large liner to ensure that the deionized water is not in contact with the dried gel; will be provided withTaking out the reaction kettle after reacting for 72 hours at 120 ℃, and quenching; and drying at 120 ℃ for 5h and calcining at 550 ℃ for 6h to obtain the hierarchical pore ZSM-5 nano zeolite which is marked as a sample 2, wherein the sample 2 simultaneously contains micropores and mesopores.

Example 3

(1) Preparing seed crystal guide glue: uniformly mixing a tetraethyl silicate silicon source, tetrapropylammonium hydroxide and deionized water according to a molar ratio of 0.35:1:1:20, stirring at room temperature for 12 hours, transferring to a polytetrafluoroethylene reaction kettle, and treating at 100 ℃ for 24 hours;

(2) preparing hierarchical pore ZSM-5 nano zeolite: uniformly stirring silica gel, aluminum sulfate and deionized water according to the molar ratio of 1:0.01:20, and adding the contained SiO₂The SiO in the silicon source added in the step (2)₂The seed crystal guide glue with the content of 20wt% is stirred for 2 hours at room temperature; then transferring the mixture into an oven at 70 ℃ for drying for 12 h; placing the dried gel in a small liner of a polytetrafluoroethylene reaction kettle, placing the small liner in a large liner of the polytetrafluoroethylene reaction kettle, and adding 2.0mL of deionized water into the large liner to ensure that the deionized water is not in contact with the dried gel; taking out the reaction kettle after reacting for 72 hours at 120 ℃, and quenching; and drying at 120 ℃ for 5h and calcining at 550 ℃ for 6h to obtain the hierarchical pore ZSM-5 nano zeolite which is marked as a sample 3, wherein the sample 3 simultaneously contains micropores and mesopores.

XRD (X-ray diffraction) pattern analysis is carried out on the samples 1-3 prepared in the examples 1-3, and as shown in figure 1, compared with a standard pattern (00-049-.

The foregoing is merely a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.