阅读说明：本技术 一种中空mfi沸石材料及其制备方法 (Hollow MFI zeolite material and preparation method thereof ) 是由 李俊杰 沈宏宇 朱向学 李秀杰 谢素娟 陈福存 刘珍妮 曲令多 安杰 徐龙伢 于 2020-06-01 设计创作，主要内容包括：本申请提供了一种中空MFI沸石材料,所述中空MFI沸石材料具有中空结构；所述中空结构介于ZSM-5壳层和Silicalite-1核层中间。并提供了该材料的制备方法,至少包括以下步骤：将含有铝源、硅源、晶种、水、有机溶剂和调节剂的原料混合物在80～150℃下预晶化1～48h,再加入模板剂R,在100～250℃下晶化2～120h,得到所述的中空MFI沸石材料。该材料具有类似“眼睛状”结构,壳层厚度灵活可控,制备方法具有操作简单、原料廉价易得、单釜产量高和可重复性好等特点。(A hollow MFI zeolite material having a hollow structure; the hollow structure is arranged between a ZSM-5 shell layer and a Silicalite-1 core layer. And provides a preparation method of the material, which at least comprises the following steps: pre-crystallizing a raw material mixture containing an aluminum source, a silicon source, a seed crystal, water, an organic solvent and a regulator at the temperature of 80-150 ℃ for 1-48 h, adding a template agent R, and crystallizing at the temperature of 100-250 ℃ for 2-120 h to obtain the hollow MFI zeolite material. The material has a structure similar to an eye shape, the thickness of a shell layer is flexible and controllable, and the preparation method has the characteristics of simple operation, cheap and easily obtained raw materials, high single-kettle yield, good repeatability and the like.)

1. A hollow MFI zeolite material, characterized in that the hollow MFI zeolite material has a hollow structure; the hollow structure is arranged between a ZSM-5 shell layer and a Silicalite-1 core layer.

2. The hollow MFI zeolite material of claim 1, wherein the hollow MFI zeolite material has a grain size of 0.1 to 3 μm.

3. A method of producing a hollow MFI zeolite material as claimed in any of claims 1-2, characterized by at least the steps of:

pre-crystallizing a raw material mixture containing an aluminum source, a silicon source, a seed crystal, water, an organic solvent and a regulator at the temperature of 80-150 ℃ for 1-48 h, adding a template agent R, and crystallizing at the temperature of 100-250 ℃ for 2-120 h to obtain the hollow MFI zeolite material.

4. The preparation method according to claim 3, wherein the molar ratio of the raw materials in the raw material mixture is:

SiO₂/Al₂O₃＝30～1000；

regulator/SiO₂＝0.05～0.60；

H₂O/SiO₂＝15～200；

The seed crystal is selected from Silicalite-1 molecular sieve;

the mass ratio of the seed crystal to the silicon source is as follows:

seed/SiO₂＝1wt％～30wt％；

Wherein the aluminum source contains Al₂O₃Calculating the mole number of the active carbon;

the silicon source and SiO contained in the silicon source₂Calculating the mole number or the mass number of the catalyst;

the seed crystal contains SiO₂And (4) calculating the mass number of the product.

5. The method according to claim 3, wherein the organic solvent is at least one selected from methanol, ethanol, n-propanol and isopropanol.

6. The preparation method according to claim 3, wherein the molar ratio of the organic solvent to the silicon source is:

organic solvent/SiO₂＝0.10～5.00。

7. The preparation method according to claim 3, wherein the template R is at least one selected from the group consisting of tetrapropylammonium hydroxide, tetrapropylammonium bromide, n-butylamine, and 1, 6-hexamethylenediamine;

preferably, the template agent R is added in a molar amount range of:

R/SiO₂＝0.02～2.00。

8. the preparation method according to claim 3, wherein the silicon source is at least one selected from silica sol, water glass, silica gel and white carbon black;

the aluminum source is selected from at least one of sodium metaaluminate, aluminum nitrate, aluminum sulfate and aluminum chloride;

the regulator is selected from inorganic base or inorganic acid.

9. The method according to claim 8,

the inorganic base is at least one selected from sodium hydroxide;

the inorganic acid is at least one of sulfuric acid and hydrochloric acid.

10. The hollow MFI zeolite material of claims 1-2 and the hollow MFI zeolite material prepared by the preparation method of any one of claims 3-9 are used in catalytic cracking reactions, hydroisomerization reactions, catalytic cracking reactions, hydrodewaxing reactions, and alkylation reactions.

Technical Field

The application relates to a hollow MFI zeolite material and a preparation method thereof, belonging to the field of zeolite molecular sieves.

Background

Zeolites are microporous crystalline materials having a high specific surface area and a high micropore volume with regular channels and cages. Meanwhile, the zeolite also has very high thermal stability and hydrothermal stability, and can keep good stability in some high-temperature hydrothermal reactions. Thus, zeolites have a wide range of applications in heterogeneously catalyzed reactions, particularly in petroleum refining and petrochemical processes, such as: catalytic cracking reaction, hydroisomerization reaction, catalytic cracking reaction, hydrodewaxing reaction and the like, and also has very many applications in alkylation reactions such as benzene and propylene, benzene and ethylene, toluene and methanol, toluene disproportionation and the like.

In addition, the zeolite may be used as a host material for encapsulating metal nanoclusters, nanoparticles, or the like, and may be used as a metal or metal oxide catalyst or an acid/alkali-metal/metal oxide bifunctional catalyst. In recent years, hollow zeolite encapsulated metal materials are concerned, and mainly benefit from the confinement effect of a molecular sieve shell, so that metal sintering and loss can be prevented, meanwhile, a reactant contacting a metal site can be screened, the selectivity of a target product is improved, in addition, the diffusion rate of the product can be improved, and the catalytic stability is improved. At present, the preparation method of the hollow zeolite mainly comprises a post-treatment method and a template method: the post-treatment method is prepared by selectively removing silicon or aluminum through alkali treatment or acid treatment, the preparation process is complex, and the requirement on the matrix property is high; the template method includes a hard template method and a soft template method, wherein the soft template method is a method of directly synthesizing hollow zeolite by adding (NMP, EDTA, etc.) during synthesis. The hard template method generally obtains hollow zeolite by growing zeolite outside silicon spheres or carbon spheres and removing a template, and has complex preparation process and higher cost.

In summary, the conventional method for directly synthesizing the hollow zeolite material is complicated and requires the addition of a hard template and a soft template. Therefore, there is still a need to develop a simple and economical method for synthesizing a novel hollow zeolite material.

Disclosure of Invention

According to one aspect of the application, the hollow MFI zeolite material is provided, the product appearance is regular and uniform, the hollow structure is between a ZSM-5 shell layer and a Silicalite-1 core layer, the hollow structure is similar to an eye-shaped structure, and the thickness of the shell layer is flexible and controllable.

A hollow MFI zeolite material having a hollow structure; the hollow structure is arranged between a ZSM-5 shell layer and a Silicalite-1 core layer.

Optionally, the hollow MFI zeolite material has a grain size of 0.1 to 3 μm.

Optionally, the upper limit of the grain size of the hollow MFI zeolite material is selected from 0.25 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm; the lower limit is selected from 0.1 μm, 0.25 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm or 2.5 μm.

According to another aspect of the application, the hollow MFI zeolite material is prepared by a two-stage crystallization method of a one-pot two-step low-temperature amine-free method and a high-temperature template method, and the template-free crystallization and the organic template-oriented crystallization are combined together to realize the controllable preparation of the eye-shaped hollow zeolite.

A preparation method of a hollow MFI zeolite material at least comprises the following steps:

pre-crystallizing a raw material mixture containing an aluminum source, a silicon source, a seed crystal, water, an organic solvent and a regulator at the temperature of 80-150 ℃ for 1-48 h, adding a template agent R, and crystallizing at the temperature of 100-250 ℃ for 2-120 h to obtain the hollow MFI zeolite material.

Optionally, pre-crystallizing a raw material mixture containing an aluminum source, a silicon source, a seed crystal, water, an organic solvent and a regulator at 80-140 ℃ for 10-36 h, adding a template agent R, and crystallizing at 100-250 ℃ for 36-60 h to obtain the hollow MFI zeolite material.

Optionally, the upper limit of the temperature of the pre-crystallization is selected from 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃; the lower limit is selected from 80 deg.C, 90 deg.C, 100 deg.C, 110 deg.C, 120 deg.C, 130 deg.C or 140 deg.C.

Optionally, the upper limit of the time for the pre-crystallization is selected from 2h, 6h, 10h, 15h, 20h, 24h, 30h, 36h, 42h or 48 h; the lower limit of the pre-crystallization time is selected from 1h, 2h, 6h, 10h, 15h, 20h, 24h, 30h, 36h or 42 h.

Optionally, the upper limit of the temperature of crystallization is selected from 110 ℃, 150 ℃, 170 ℃, 200 ℃, 220 ℃ or 250 ℃; the lower limit is selected from 100 deg.C, 110 deg.C, 150 deg.C, 170 deg.C, 200 deg.C or 220 deg.C.

Optionally, the upper limit of the crystallization time is selected from 6h, 12h, 24h, 36h, 48h, 50h, 60h, 80h, 100h, or 120 h; the lower limit of the pre-crystallization time is selected from 2h, 6h, 12h, 24h, 36h, 48h, 50h, 60h, 80h or 100 h.

Optionally, in the raw material mixture, the molar ratio of the raw materials is:

SiO₂/Al₂O₃＝30～1000；

regulator/SiO₂＝0.05～0.60；

H₂O/SiO₂＝15～200；

The seed crystal is selected from Silicalite-1 molecular sieve;

the mass ratio of the seed crystal to the silicon source is as follows:

seed/SiO₂＝1wt％～30wt％；

Wherein the aluminum source contains Al₂O₃Calculating the mole number of the active carbon;

the silicon source and SiO contained in the silicon source₂Calculating the mole number or the mass number of the catalyst;

the seed crystal contains SiO₂And (4) calculating the mass number of the product.

Optionally, in the raw material mixture, the raw materials are in the following proportions:

SiO₂/Al₂O₃＝80～480；

regulator/SiO₂＝0.14～0.40；

H₂O/SiO₂＝30～80；

seed/SiO₂＝2wt％～16wt％。

Optionally, the SiO₂/Al₂O₃The upper limit of the molar ratio is selected from 50, 80, 100, 160, 200, 300, 320, 400, 480, 500, 600, 700, 800, 900 or 1000; the lower limit is selected from 30, 50, 80, 100, 160, 200, 300, 320, 400, 480, 500, 600, 700, 800, or 900.

Optionally, the regulator/SiO₂The upper limit of the molar ratio is selected from 0.1, 0.14, 0.2, 0.25, 0.3, 0.4, 0.5 or 0.6; the lower limit is selected from 0.05, 0.1, 0.14, 0.2, 0.25, 0.3, 0.4 or 0.5.

Alternatively, the H₂O/SiO₂The upper limit of the molar ratio is selected from 30, 40, 43, 50, 60, 80, 100, 150 or 200; the lower limit is selected from 15, 30, 40, 43, 50, 60, 80, 100, or 150.

Optionally, the seed/SiO₂The upper limit of the mass ratio of (A) is selected from 2 wt%, 4 wt%, 6 wt%, 8 wt%, 12 wt%, 16 wt%, 20 wt%, 25 wt% or 30 wt%; the lower limit is selected from 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 12 wt%, 16 wt%, 20 wt% or 25 wt%.

Optionally, the organic solvent is selected from at least one of methanol, ethanol, n-propanol and isopropanol.

Optionally, the molar ratio of the organic solvent to the silicon source is:

organic solvent/SiO₂＝0.10～5.00。

Optionally, the molar ratio of the organic solvent to the silicon source is:

organic solvent/SiO₂＝0.5～2.38。

Alternatively, the upper limit of the molar ratio of the organic solvent to the silicon source is selected from 0.25, 0.50, 1.00, 1.50, 2.00, 2.38, 2.50, 3.00, 3.50, 4.00, 4.50, or 5.00; the lower limit is selected from 0.10, 0.25, 0.50, 1.00, 1.50, 2.00, 2.38, 2.50, 3.00, 3.50, 4.00, or 4.50.

In the application, the pre-crystallization temperature is about 80-150 ℃, the relative temperature is low, and the hollow MFI zeolite material with a hollow structure is finally prepared under the action of an organic solvent.

Optionally, the template agent R is selected from at least one of tetrapropylammonium hydroxide, tetrapropylammonium bromide, n-butylamine and 1, 6-hexamethylenediamine.

Alternatively, the template R is added in a molar amount range of:

R/SiO₂＝0.02～2.00。

alternatively, the template R is added in a molar amount range of:

R/SiO₂＝0.08～0.30。

alternatively, the upper limit of the added molar amount of templating agent R is selected from 0.08, 0.10, 0.15, 0.20, 0.30, 0.50, 1.00, 1.50, or 2.00; the lower limit is selected from 0.02, 0.08, 0.10, 0.15, 0.20, 0.30, 0.50, 1.00 or 1.50.

Optionally, the silicon source is selected from at least one of silica sol, water glass, silica gel and white carbon black.

Optionally, the aluminum source is selected from at least one of sodium metaaluminate, aluminum nitrate, aluminum sulfate, and aluminum chloride.

Optionally, the modifier M is selected from an inorganic base or an inorganic acid.

Optionally, the inorganic base is selected from at least one of sodium hydroxide.

Optionally, the inorganic acid is selected from at least one of sulfuric acid and hydrochloric acid.

The alkalinity of the raw material mixture is adjusted by adding an inorganic base or an inorganic acid.

According to another aspect of the application, the hollow MFI zeolite material and the application of the hollow MFI zeolite material prepared by the preparation method in catalytic cracking reaction, hydroisomerization reaction, catalytic cracking reaction, hydrodewaxing reaction and alkylation reaction are provided.

In this application, "TPABr" refers to tetrapropylammonium bromide.

In the present application, "TPAOH" refers to tetrapropylammonium hydroxide.

The beneficial effects that this application can produce include:

the hollow MFI zeolite material provided by the application has a similar eye-shaped structure, wherein the hollow structure is between a ZSM-5 shell layer and a Silicalite-1 core layer, the thickness of the shell layer is flexible and controllable, the synthesis method of the hollow MFI zeolite material provided by the application adopts a two-stage crystallization method combining a one-pot two-step low-temperature amine-free method and a high-temperature template method, is not limited by a water-silicon ratio and a silicon source, has the characteristics of simple operation, cheap and easily available raw materials, high single-pot yield, good repeatability and the like, and is easy for industrial amplification production.

Drawings

Fig. 1 is an X-ray diffraction pattern of sample # 1 of example 1.

FIG. 2 is a TEM image of sample No. 1 of example 1, wherein FIG. (a) is a high magnification TEM image (500nm) and FIG. (b) is a low magnification TEM image (1 μm).

FIG. 3 is a transmission electron micrograph of sample No. 1 to 3 of examples 1 to 3, wherein FIG. (a) is a transmission electron micrograph (500nm) of sample No. 1, FIG. (b) is a transmission electron micrograph (1 μm) of sample No. 2, and FIG. (c) is a transmission electron micrograph (1 μm) of sample No. 3.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified. Unless otherwise specified, the analytical methods in this application are generally performed using conventional analytical methods and conventional instrumentation.

The analysis method in the examples of the present application is as follows:

x-ray diffraction pattern (XRD) analysis, instrument model SmartLab9, operating at 40KV and 100mA, respectively. The scanning range 2 theta is 5-50 DEG, and the scanning speed is 8 DEG/min.

The appearance test analysis is carried out by using a Transmission Electron Microscope (TEM), the model of the TEM is a transmission electron microscope HT7700 type of Hitachi company, and the accelerating voltage is 100 kV.

In embodiments, "Seed" refers to a Seed.

Example 1

Under the stirring condition, the following proportions are adopted: adding silica sol, aluminum sulfate, sodium hydroxide, deionized water, ethanol and Silicalite-1 liquid crystal seeds into a reaction kettle in a certain sequence. The raw materials are in proportion (molar composition): SiO 2₂/Al₂O₃＝480，Na₂O/SiO₂＝0.14，Seed/SiO₂8 wt% (SiO in seed crystal)₂Mass of SiO₂8% by mass) of H₂O/SiO₂43, ethanol/SiO₂2.38. Stirring uniformly, placing in a crystallization kettle, and dynamically crystallizing at 130 ℃ for 10 hours; the reaction was quenched with tap water and then TPABr (TPABr/SiO) was added₂0.15), crystallizing at 170 ℃ for 60 hours, cooling to room temperature, washing to be neutral by deionized water, and drying at 120 ℃ overnight to obtain the molecular sieve raw powder which is marked as sample # 1.

Example 2

Under the condition of stirring, white carbon black, aluminum nitrate, sodium hydroxide, deionized water, ethanol and Silicalite-1 solid crystal seeds are added into a reaction kettle according to the following proportion in a certain order. The raw materials are in proportion (molar composition): SiO 2₂/Al₂O₃＝320，Na₂O/SiO₂＝0.20，Seed/SiO₂4% by weight of ethanol/SiO₂＝1.00，H₂O/SiO₂30. Dynamic crystallization is carried out for 15 hours at 100 ℃; the reaction was quenched with tap water and then TPAOH (TPAOH/SiO) was added₂0.08), crystallizing at 170 ℃ for 24 hours, cooling to room temperature, washing to be neutral by deionized water, and drying at 120 ℃ overnight to obtain the molecular sieve raw powder which is marked as sample No. 2.

Example 3

Under the condition of stirring, water glass, aluminum trichloride, 0.2mol/L hydrochloric acid solution, deionized water, ethanol and liquid Silicalite-1 seed crystal are added into a reaction kettle in a certain sequence according to the following proportion. The raw material proportionComprises the following components in percentage by mole: SiO 2₂/Al₂O₃＝160，Na₂O/SiO₂＝0.25，H₂O/SiO₂80, ethanol/SiO₂＝1.50，Seed/SiO₂16 wt%. Dynamic crystallization is carried out for 24 hours at 80 ℃; the reaction was quenched with tap water and then n-butylamine (n-butylamine/SiO) was added₂0.30), crystallizing at 170 ℃ for 48 hours, cooling to room temperature, washing to be neutral by deionized water, and drying at 120 ℃ overnight to obtain the molecular sieve raw powder which is marked as sample # 3.

Example 4

Under the condition of stirring, adding silica sol, aluminum trichloride, NaOH, deionized water, ethanol and Silicalite-1 seed crystal into a reaction kettle in a certain order according to the following proportion. The raw materials are in proportion (molar composition): SiO 2₂/Al₂O₃＝200，Na₂O/SiO₂＝0.40，H₂O/SiO₂40, ethanol/SiO₂＝0.50，Seed/SiO₂2 wt%. Dynamic crystallization is carried out for 24 hours at 140 ℃; the reaction was quenched with tap water and then 1, 6-hexanediamine (1, 6-hexanediamine/SiO) was added₂0.20), crystallizing at 170 ℃ for 48 hours, cooling to room temperature, washing to be neutral by deionized water, and drying at 120 ℃ overnight to obtain the molecular sieve raw powder which is marked as sample No. 4.

Example 5

Under the condition of stirring, silica gel, aluminum sulfate, NaOH, deionized water and Silicalite-1 liquid crystal seeds are added into a reaction kettle according to the following proportion in a certain order. The raw materials are in proportion (molar composition): SiO 2₂/Al₂O₃＝80，Na₂O/SiO₂＝0.20，H₂O/SiO₂＝50，Seed/SiO₂8 wt.% methanol/SiO₂2.00. Dynamic crystallization is carried out for 36 hours at 80 ℃; the reaction was quenched with tap water and then TPAOH solution and TPABr (TPA) were added⁺/SiO₂0.15), crystallizing at 170 ℃ for 36 hours, cooling to room temperature, washing to be neutral by deionized water, and drying at 120 ℃ overnight to obtain molecular sieve raw powder which is marked as sample No. 5.

Example 6

XRD testing of samples # 1-5, exemplified by sample # 1, and FIG. 1 is the powder X-ray diffraction pattern of sample # 1, showing that this sample has a typical MFI topology. The XRD patterns of samples 2-5# are similar to that of sample 1 #.

Example 7

Transmission electron microscopy analysis was performed on samples 1 to 5# using sample 1# as an example, fig. 2 is a TEM image of sample 1#, fig. (a) is a high magnification transmission electron microscopy image, and fig. (b) is a low magnification transmission electron microscopy image, which shows that it has an obvious hollow structure between the core layer and the shell layer. FIG. 3 is a transmission electron micrograph of sample # 1 to # 3, wherein FIG. (a) is a transmission electron micrograph of sample # 1, FIG. (b) is a transmission electron micrograph of sample # 2, and FIG. (c) is a transmission electron micrograph of sample # 3. It can be seen that the TEM results show that it has an "eye-like" hollow zeolite structure; the grain size is 0.1 to 3 μm.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.