Zsm-5 nanocrystal material with hollow multi-level pores and preparation method and application thereof

Abstract

The application relates to a ZSM-5 nanocrystal material with hollow multi-stage pores and a preparation method and application thereof, the ZSM-5 nanocrystal material has a closed hollow structure, the average grain size of the ZSM-5 nanocrystal material is 0.2-3.0 mu m, the ratio of the bulk phase silicon aluminum molar ratio to the surface silicon aluminum molar ratio is 1.0-1.5, the total specific surface area is 340-420 m 2 / g, the mesopore specific surface area is 40-150 m 2 / g, and the N2 adsorption and desorption curve presents an H4 type hysteresis loop. The ZSM-5 nanocrystal material has a closed hollow multi-stage pore structure and relatively excellent catalytic performance.

Description

TECHNICAL FIELD

[0001] The present application relates to a ZSM-5 nanocrystalline material with hollow multi-level pores and a preparation method and application thereof. BACKGROUND

[0002] Hollow materials have special intracapsular microenvironment and unique space confinement effect, and show excellent performance in heterogeneous catalysis, biomedicine, adsorption separation and energy storage. Hollow ZSM-5 molecular sieve has a nanoscale multi-level pore shell and a relatively closed internal structure, has the advantages of strong acidity, excellent diffusion performance and outstanding encapsulation capacity, and is a high-value material with great potential in industrial catalysis and adsorption separation.

[0003] CN106082263B develops a shell layer rich in pores of nanometer hollow ZSM-5 molecular sieve, which is prepared by mixing tetraethyl orthosilicate, tetrapropylammonium hydroxide, aluminum nitrate, sodium hydroxide and deionized water, then aging, crystallizing, centrifuging, washing, drying and calcining the solution to obtain nanometer ZSM-5 molecular sieve; the nanometer ZSM-5 molecular sieve is added into an inorganic alkali aqueous solution, stirred for 10-50h, separated, washed and dried to obtain nanometer ZSM-5 with a hollow structure, and then treated with a mixed alkali aqueous solution to obtain a shell layer rich in pores of nanometer hollow ZSM-5 molecular sieve. The product prepared has a crystal grain size of 50-100nm, and the molecular sieve crystal grain is small, and the shell layer is rich in large pores, but the hydrothermal stability and thermal stability are limited.

[0004] CN107381593A develops a hollow spherical multi-level pore ZSM-5 molecular sieve, which is prepared into a hollow structure by one-step hydrothermal synthesis of ZSM-5 molecular sieve by a soft template method, which can improve the activity of catalytic phenol hydroxylation reaction. However, the introduction of soft template increases the synthesis cost, and the morphology of the prepared ZSM-5 molecular sieve has obvious "opening", which causes the specific surface area of the molecular sieve to decrease, and affects the structural stability. SUMMARY

[0005] The purpose of the present application is to provide a ZSM-5 nanocrystalline material with hollow multi-level pores and a preparation method and application thereof. The closed hollow structure of the ZSM-5 nanocrystalline material has good hydrothermal stability, and the rich mesoporous distribution provides multi-directional diffusion channels for the nanocrystalline material, which can significantly improve the diffusion performance and accessibility of active centers, and has excellent cracking performance.

[0006] To achieve the above object, the first aspect of the present application provides a ZSM-5 nanocrystalline material with hollow multi-level pores, wherein the ZSM-5 nanocrystalline material has a closed hollow structure, the average grain size of the ZSM-5 nanocrystalline material is 0.2-3.0 μm, the ratio of the bulk phase silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio is 1.0-1.5, the total specific surface area is 340-420 m 2 / g, the mesopore specific surface area is 40-150 m 2 / g, and the N2 adsorption-desorption curve presents a H4 type hysteresis loop.

[0007] Optionally, the average grain size of the ZSM-5 nanocrystalline material is 0.4-2.5 μm.

[0008] Optionally, the ratio of the bulk phase silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the ZSM-5 nanocrystalline material is 1.0-1.3.

[0009] Optionally, the total specific surface area of the ZSM-5 nanocrystalline material is 340-420 m 2 / g, preferably 360-400 m 2 / g; the mesopore specific surface area is 40-150 m 2 / g, preferably 50-140 m 2 / g; the micropore specific surface area is 190-380 m 2 / g, preferably 190-360 m 2 / g.

[0010] Optionally, the relative crystallinity of the ZSM-5 nanocrystalline material is 75-95%.

[0011] The second aspect of the present application provides a method for preparing the ZSM-5 nanocrystalline material, which comprises:

[0012] (1) mixing and stirring a first organic silicon source and a first solvent at 30-50 ℃ for 0.5-5 hours, then increasing the temperature to 70-100 ℃ and mixing and stirring for 2-10 hours, mixing the obtained mixed liquid with a first template agent at 20-30 ℃ for 0.5-3.0 hours to obtain a first mixed product;

[0013] (2) mixing a first alkali metal hydroxide in terms of alkali metal oxide, a second solvent and a first aluminum source in terms of Al2O3 in a molar ratio of (1.5-5):(60-350):1 at 20-80 ℃ for 0.5-2.0 hours to obtain a second mixed product;

[0014] (3) mixing the first mixed product with the second mixed product and then performing dynamic crystallization, taking out the obtained solid and performing a first calcination to obtain a first solid product;

[0015] (4) mixing the first solid product with a first solution containing base, and then raising the temperature at a rate of 1-5 ℃ / min to a reaction temperature, and then reacting at the reaction temperature for 10-90 min to obtain a second solid product; wherein the reaction temperature is 60-90 ℃, and the content of base in the first solution containing base is 0.45-2 mol / L;

[0016] (5) subjecting the second solid product to first ammonium exchange, and optionally third calcination, to obtain the ZSM-5 nanocrystal material with hollow hierarchical pores; or,

[0017] The method comprises:

[0018] S1, mixing a second inorganic silicon source and a third solvent at 30-50 ℃ for 0.5-3.0 hours, and then subjecting the obtained third mixed product to first and second hydrothermal treatments in sequence to obtain a fourth mixed product; wherein the first hydrothermal treatment is carried out at a temperature of 80-150 ℃ for 1-6 hours; and the second hydrothermal treatment is carried out at a temperature of 160-180 ℃ for 12-60 hours;

[0019] S2, mixing a second alkali hydroxide in terms of alkali metal oxide, a fourth solvent and a second aluminum source in terms of Al2O3 at a molar ratio of (1.5-5):(60-350):1 at 20-80 ℃ for 0.5-2.0 hours to obtain a fifth mixed product;

[0020] S3, mixing the fourth mixed product and the fifth mixed product, and then subjecting the obtained mixture to third hydrothermal treatment, taking out the obtained solid and subjecting it to second calcination to obtain a third solid product;

[0021] S4, mixing the third solid product with a second solution containing base, and then raising the temperature at a rate of 1-5 ℃ / min to a reaction temperature, and then reacting at the reaction temperature for 10-90 min to obtain a fourth solid product; wherein the reaction temperature is 60-90 ℃, and the content of base in the second solution containing base is 0.45-2 mol / L;

[0022] S5, subjecting the fourth solid product to second ammonium exchange, and optionally fourth calcination, to obtain the ZSM-5 nanocrystal material with hollow hierarchical pores.

[0023] Optionally, the total amount of the first template agent, the first solvent and the second solvent, the molar ratio of the amount of the first alkali metal hydroxide and the first organic silicon source is (0.06-0.55):(10-100):(0.02-1.5):1, the molar ratio of the amount of the first organic silicon source and the first aluminum source is (20-500):1; wherein the first organic silicon source is calculated as SiO2, the first alkali metal hydroxide is calculated as alkali metal oxide, and the first aluminum source is calculated as Al2O3;

[0024] Preferably, in step (2), the molar ratio of the amount of the first alkali metal hydroxide, the second solvent and the first aluminum source calculated as Al2O3 is (2-4.5):(80-350):1;

[0025] Preferably, in step (4), the weight ratio of the amount of the first solid product and the first solution containing alkali is 1:(2-10); the ratio of the bulk silicon-aluminum molar ratio and the surface silicon-aluminum molar ratio of the first solid product is 1.2-5.0;

[0026] The molar ratio of the amount of the second template agent, the third solvent, the second alkali metal hydroxide and the second inorganic silicon source is (0.06-0.55):(10-100):(0.02-1.5):1, the molar ratio of the second inorganic silicon source and the second aluminum source is (20-500):1; wherein the second inorganic silicon source is calculated as SiO2, the second alkali metal hydroxide is calculated as alkali metal oxide, and the second aluminum source is calculated as Al2O3;

[0027] Preferably, in step S2, the molar ratio of the amount of the second alkali metal hydroxide, the fourth solvent and the second aluminum source calculated as Al2O3 is (2-4.5):(80-350):1;

[0028] Preferably, in step S4, the weight ratio of the amount of the third solid product and the second solution containing alkali is 1:(2-10), and the ratio of the bulk silicon-aluminum molar ratio and the surface silicon-aluminum molar ratio of the third solid product is 1.2-5.0.

[0029] Optionally, the first organic silicon source is selected from one or more of methyl orthosilicate and ethyl orthosilicate;

[0030] The second inorganic silicon source is selected from one or more of silica sol, water glass and solid silica gel;

[0031] The first template agent and the second template agent are each independently selected from one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine and hexanediamine;

[0032] The first aluminum source and the second aluminum source are each independently selected from one or more of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum isopropoxide and aluminum sol;

[0033] The first alkali hydroxide and the second alkali hydroxide are each independently selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;

[0034] The first alkali-containing solution and the second alkali-containing solution are each independently selected from one or more of sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide and barium hydroxide.

[0035] Optionally, the conditions of the dynamic crystallization include that the temperature is 160-180℃ and the time is 12-60 hours.

[0036] The conditions of the third hydrothermal treatment include that the temperature is 160-180℃ and the time is 12-60 hours.

[0037] The conditions of the first calcination and the second calcination each independently include that the temperature is 400-600℃ and the time is 2-6 hours.

[0038] Optionally, in step (5), the first ammonium exchange of the second solid product includes that the second solid product, the first ammonium source and the fifth solvent are mixed at a weight ratio of 1:(0.5-1.0):(8-10), and then the obtained mixture is reacted at 70-90℃ for 0.5-5 hours.

[0039] In step S5, the second ammonium exchange of the fourth solid product includes that the fourth solid product, the second ammonium source and the sixth solvent are mixed at a weight ratio of 1:(0.5-1.0):(8-10), and then the obtained mixture is reacted at 70-90℃ for 0.5-2 hours.

[0040] The first ammonium source and the second ammonium source are each independently selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

[0041] The third aspect of the present application provides an application of the ZSM-5 nanocrystalline material with hollow multi-level pores provided by the first aspect of the present application in petroleum chemical industry and / or fine chemical industry.

[0042] Through the above technical solution, the nanocrystalline material has a structure of hollow multi-level pores, the surface of which is mainly microporous structure and is rich in mesoporous structure, which can provide multi-directional diffusion paths, expand the limited space, effectively improve the accessibility of active centers, has the potential for catalyzing the cracking of macromolecular hydrocarbons, and the closed hollow structure makes it have good hydrothermal stability.

[0043] Other features and advantages of the present application will be illustrated in the following detailed description of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0044] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0045] Figure 1 is a TEM image of the closed hollow hierarchical-pore ZSM-5 nanocrystal material prepared in Example 1 of the present application;

[0046] Figure 2 is a TEM image of the closed hollow hierarchical-pore ZSM-5 nanocrystal material prepared in Example 2 of the present application;

[0047] Figure 3 is a TEM image of the closed hollow hierarchical-pore ZSM-5 nanocrystal material prepared in Example 3 of the present application;

[0048] Figure 4 is a TEM image of the closed hollow hierarchical-pore ZSM-5 nanocrystal material prepared in Example 4 of the present application;

[0049] Figure 5 is a desorption and adsorption curve of the closed hollow hierarchical-pore ZSM-5 nanocrystal material prepared in Example 1 of the present application;

[0050] Figure 6 is a TEM image of the parent ZSM-5 molecular sieve prepared in Comparative Example 2 of the present application;

[0051] Figure 7 is a TEM image of the nanocluster ZSM-5 molecular sieve prepared in Comparative Example 2 of the present application after alkaline treatment. DETAILED DESCRIPTION

[0052] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0053] The present application provides a ZSM-5 nanocrystal material having hollow hierarchical pores, wherein the ZSM-5 nanocrystal material has a closed hollow structure, the average crystal grain size of the ZSM-5 nanocrystal material is 0.2-3.0 μm, the ratio of the bulk phase silica-alumina molar ratio to the surface silica-alumina molar ratio is 1.0-1.5, the total specific surface area is 340-420 m 2 / g, the mesopore specific surface area is 40-150 m 2 / g, and the N2 desorption and adsorption curve presents a H4 type hysteresis loop.

[0054] According to the application, the closed hollow structure refers to a structure with a completely closed shell layer and an internal cavity with a hollow structure, and the ZSM-5 nanocrystal material has a hollow multi-level pore structure, which can improve the accessibility of the active sites of the molecular sieve, has the potential to catalyze the cracking of macromolecular hydrocarbons, and improves the modification efficiency in the process of metal or non-metal modification, and is applied to the fields of petroleum chemical industry, fine chemical industry and the like, and has good industrial application value.

[0055] In the application, the N2 adsorption-desorption curve is measured by a method well known to those skilled in the art, which will not be described herein.

[0056] In one specific embodiment of the application, the average crystal grain size of the ZSM-5 nanocrystal material is 0.2-3.0 μm, more preferably 0.4-2.5 μm, and further preferably 0.5-2.5 μm. The crystal grain size refers to the size of the widest part of the crystal grain, which can be obtained by measuring the size of the widest part of the projection surface of the crystal grain in the SEM or TEM image of the sample, and the average crystal grain size is obtained by selecting any 10 molecular sieves in the SEM or TEM image and calculating the average value.

[0057] In one specific embodiment of the application, the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the ZSM-5 nanocrystal material is 1.0-1.3. The bulk silicon-aluminum ratio is determined by the XRF method, and the surface silicon-aluminum ratio is determined by the XPS method, and the specific testing method is well known to those skilled in the art, which will not be described herein.

[0058] In one specific embodiment of the application, the total specific surface area of the ZSM-5 nanocrystal material is 340-420 m 2 / g, preferably 360-400 m 2 / g; the mesopore specific surface area is 40-150 m 2 / g, preferably 50-140 m 2 / g; and the micropore specific surface area is 190-380 m 2 / g, preferably 190-360 m 2 / g, and more preferably 260-360 m 2 / g. In the application, the total specific surface area, the mesopore specific surface area and the micropore specific surface area are obtained by BET analysis. The surface of the nanocrystal material of the application is mainly microporous, and is rich in mesoporous and macroporous structures, which can further provide multidirectional diffusion paths, expand the limited space, improve the accessibility of the active centers, and has the potential to catalyze the cracking of macromolecular hydrocarbons.

[0059] In one embodiment of the present application, the relative crystallinity of the ZSM-5 nanocrystal material is 75-95%. In the present application, the relative crystallinity of the molecular sieve is based on the XRD standard ZSM-5 molecular sieve sample of the Research Institute of Petroleum Processing, and the crystallinity of the sample is considered to be 100%.

[0060] The second aspect of the present application provides a method for preparing the ZSM-5 nanocrystal material with closed hollow hierarchical pores provided by the first aspect of the present application.

[0061] In one embodiment, the method comprises: (1) mixing and stirring a first organosilicon source and a first solvent at 30-50°C for 0.5-5 hours, then increasing the temperature to 70-100°C and mixing and stirring for 2-10 hours, mixing the obtained mixed liquid with a first template agent at 20-30°C for 0.5-3.0 hours to obtain a first mixed product; (2) mixing a first alkali hydroxide in terms of alkali metal oxide, a second solvent and a first aluminum source in terms of Al2O3 in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain a second mixed product; (3) mixing the first mixed product with the second mixed product and then performing dynamic crystallization, taking out the obtained solid and performing first calcination to obtain a first solid product; (4) mixing the first solid product with a first solution containing alkali, increasing the temperature to a reaction temperature at a temperature increasing rate of 1-5°C / min, and then reacting at the reaction temperature for 10-90 min to obtain a second solid product; wherein the reaction temperature is 60-90°C, and the content of alkali in the first solution containing alkali is 0.45-2 mol / L; (5) performing first ammonium exchange on the second solid product to obtain a ZSM-5 nanocrystal material with hollow hierarchical pores.

[0062] In one preferred embodiment of the present application, in step (1), the first organosilicon source and the first solvent are mixed and stirred at 30-50°C for 0.5-5 hours, and then the temperature is increased to 70-100°C and mixed and stirred for 2-10 hours, and in the process, the first solvent evaporated is intermittently supplemented to the system.

[0063] According to the present application, the total amount of the first template agent, the first solvent and the second solvent, the molar ratio of the amount of the first alkali metal hydroxide and the first organic silicon source can vary in a large range, for example, can be (0.06-0.55):(10-100):(0.02-1.5):1, preferably (0.1-0.50):(15-85):(0.03-1.2):1, the molar ratio of the amount of the first organic silicon source and the first aluminum source can be (20-500):1; wherein the first organic silicon source is calculated as SiO2, the first alkali metal hydroxide is calculated as alkali metal oxide (for example, when the first alkali metal hydroxide is NaOH, the first alkali metal hydroxide is calculated as Na2O), and the first aluminum source is calculated as Al2O3. In an embodiment, the total molar amount of OH contained in the first template agent and the first alkali metal hydroxide and the molar amount of the first organic silicon source calculated as SiO2 are in the ratio of (0.01-1.5):1, preferably (0.02-1.2):1. -

[0064] In the present application, in step (1), the mixing of the first template agent, the first organic silicon source and the first solvent at 30-50°C for 0.5-3.0 hours means that after the first template agent, the first organic silicon source and the first solvent are mixed together, they are then mixed and stirred at 30-50°C for 0.5-3.0 hours.

[0065] According to the present application, in step (2), the molar ratio of the amount of the first alkali metal hydroxide calculated as alkali metal oxide, the second solvent and the first aluminum source calculated as Al2O3 can vary in a large range, for example, can be (2-4.5):(80-350):1.

[0066] According to the present application, in step (3), the dynamic crystallization is well known to those skilled in the art, and the conditions of the dynamic crystallization can include a temperature of 80-200°C and a time of 4-80 hours: preferably, a temperature of 160-180°C and a time of 12-60 hours.

[0067] According to the present application, in step (4), the weight ratio of the amount of the first solid product and the first solution containing alkali can be 1:(2-10), preferably 1:(8-10); the ratio of the bulk silicon-aluminum molar ratio and the surface silicon-aluminum molar ratio of the first solid product can be 1.2-5.0.

[0068] ​According to the present application, in step (5), the first ammonium exchange of the second solid product comprises: mixing the second solid product, a first ammonium source and a fifth solvent in a weight ratio of 1:(0.5-1.0):(8-10), and then reacting the obtained mixture at 70-90°C for 0.5-5 hours. The first ammonium source is selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate. Optionally, the product of the first ammonium exchange is filtered, washed and dried; optionally, the product of the first ammonium exchange is subjected to third calcination, preferably, the product of the first ammonium exchange is filtered, washed and dried before being subjected to third calcination; the temperature of the third calcination can be 400-600°C, and the time can be 1-24 hours, preferably 1-10 hours or 1.5-6 hours, more preferably, the temperature is 450-580°C, and the time is 2-4.5 hours.

[0069] In one embodiment, the ZSM-5 nanocrystalline material with hollow hierarchical pores has a mesopore specific surface area increased by 100-500% compared to the first solid product, a mesopore volume increased by 150-600%, and a total acid amount increased by 50-250%.

[0070] In another embodiment, the method comprises: S1, mixing a second template agent, a second inorganic silicon source and a third solvent at 30-50°C for 0.5-3.0 hours, and then sequentially subjecting the obtained third mixed product to first hydrothermal treatment and second hydrothermal treatment to obtain a fourth mixed product; wherein the first hydrothermal treatment has a temperature of 80-150°C and a time of 1-6 hours; the second hydrothermal treatment has a temperature of 160-180°C and a time of 12-60 hours; S2, mixing a second alkali metal hydroxide in a molar ratio of (1.5-5):(60-350):1 in terms of alkali metal oxides, a fourth solvent and a second aluminum source in terms of Al2O3 at 20-80°C for 0.5-2.0 hours to obtain a fifth mixed product; S3, mixing the fourth mixed product and the fifth mixed product, and then subjecting the obtained mixture to third hydrothermal treatment, taking out the obtained solid and subjecting it to second calcination to obtain a third solid product; S4, mixing the third solid product with a second solution containing alkali, and then increasing the temperature to a reaction temperature at a temperature increasing rate of 1-5°C / min, and then reacting at the reaction temperature for 10-90 min to obtain a fourth solid product; wherein the reaction temperature is 60-90°C, and the content of alkali in the second solution containing alkali is 0.45-2 mol / L; S5, subjecting the fourth solid product to second ammonium exchange to obtain the ZSM-5 nanocrystalline material with hollow hierarchical pores.

[0071] According to the present application, the total amount of the second template agent, the third solvent and the fourth solvent, the molar ratio of the amount of the second alkali metal hydroxide and the second inorganic silicon source is (0.06-0.55) : (10-100) : (0.02-1.5) : 1, preferably (0.10-0.50) : (15-85) : (0.03-1.2) : 1, and the molar ratio of the second inorganic silicon source to the second aluminum source is (20-500) : 1; wherein the second inorganic silicon source is calculated as SiO2, the second alkali metal hydroxide is calculated as alkali metal oxide (for example, when the second alkali metal hydroxide is NaOH, the second alkali metal hydroxide is calculated as Na2O), and the second aluminum source is calculated as Al2O3. In one embodiment, the ratio of the total molar amount of OH- in the second template agent and the second alkali metal hydroxide to the molar amount of the second inorganic silicon source calculated as SiO2 (denoted as OH / SiO2) is (0.01-1.5) : 1, preferably (0.02-1.2) : 1.

[0072] According to the present application, the hydrothermal treatment is well known to those skilled in the art, for example, it can be carried out in a heat-resistant sealed container. The present application does not limit the conditions of the hydrothermal treatment, which can be carried out under the autogenous pressure of the reaction system or under an external pressure, preferably under the autogenous pressure.

[0073] According to the present application, in step S2, the molar ratio of the amount of the second alkali metal hydroxide calculated as alkali metal oxide, the fourth solvent and the second aluminum source calculated as Al2O3 is (2-4.5) : (80-350) : 1.

[0074] In one embodiment, in step S3, the conditions of the third hydrothermal treatment include 160-180℃, and the time is 12-60 hours.

[0075] According to the present application, in step S4, the weight ratio of the amount of the third solid product to the second solution containing alkali is 1 : (2-10), preferably 1 : (8-10), and the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the third solid product is 1.2-5.0.

[0076] According to the present application, in step S5, the second ammonium exchange of the fourth solid product comprises: mixing the fourth solid product, a second ammonium source and a sixth solvent in a weight ratio of 1:(0.5-1.0):(8-10), and then reacting the mixture obtained at 70-90°C for 0.5-2 hours. The second ammonium source is selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate. Optionally, the product obtained by the second ammonium exchange is filtered, washed and dried; optionally, the product obtained by the second ammonium exchange is subjected to a fourth calcination, preferably, the product obtained by the second ammonium exchange is filtered, washed, dried and then subjected to a fourth calcination; the fourth calcination is performed at a temperature of 400-600°C for 1-24 hours, preferably 1-10 hours or 1.5-6 hours, more preferably at a temperature of 450-580°C for 2-4.5 hours.

[0077] According to the present application, compared with the third solid product, the ZSM-5 nanocrystalline material with hollow multi-level pores has a mesopore specific surface area increased by 100-500%, a mesopore volume increased by 150-600% and a total acid amount increased by 50-250%.

[0078] According to the present application, the calcination is a conventional technical means for those skilled in the art, and can be performed in a muffle furnace, a tube furnace or the like. In an embodiment, the conditions of the first calcination and the second calcination are each independently selected from a temperature of 400-600°C and a time of 2-6 hours, preferably a temperature of 450-580°C and a time of 3-5 hours.

[0079] According to the present application, the first organic silicon source is selected from one or more of methyl orthosilicate and ethyl orthosilicate; the second inorganic silicon source is selected from one or more of silica sol, water glass and solid silica gel; the first template agent and the second template agent are each independently selected from one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine and hexanediamine; the first aluminum source and the second aluminum source are each independently selected from one or more of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum isopropyl alcohol and aluminum sol; the first alkali metal hydroxide and the second alkali metal hydroxide are each independently selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; the first alkali-containing solution and the second alkali-containing solution are each independently selected from one or more of sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide and barium hydroxide.

[0080] According to the present application, in an embodiment, the first solvent, the second solvent, the third solvent, the fourth solvent, the fifth solvent and the sixth solvent are each water.

[0081] The third aspect of the present application provides a use of the ZSM-5 nanocrystalline material with hollow multi-level pores provided by the first aspect of the present application in petroleum chemical industry and / or fine chemical industry.

[0082] The application will be further described by the following examples, but the application is not limited in any way by the examples.

[0083] The raw materials used in the following examples and comparative examples are commercially available, unless otherwise specified.

[0084] In the examples and comparative examples, the crystallite size of the molecular sieve is measured by TEM, 10 crystallite sizes are randomly measured and their average value is taken as the average crystallite size of the molecular sieve sample.

[0085] The bulk silica-alumina ratio of the sample is determined by XRF method, the instrument is X-ray fluorescence spectrometer of ZSX Primus II (Rigaku) type; the test conditions are: excitation voltage 50 kV, excitation current 50 mA, rhodium palladium. The intensity of the spectrum peak of each element is determined by a scintillation counter and a proportional counter, and the element composition analysis of the molecular sieve is carried out.

[0086] The surface silica-alumina ratio of the sample is determined by XPS method, the instrument is X-ray photoelectron spectrometer of ESCALab250 type of ThermoFisher company, the test conditions are: the excitation source is monochromatic Al Kα X-ray, the excitation energy is 1496.6 eV, and the power is 150 W. The electron binding energy is corrected by the C1s peak of the contaminant carbon (284.8 eV).

[0087] The total specific surface area, mesopore specific surface area, micropore specific surface area and N2 adsorption-desorption curve of the sample are detected by BET method. The instrument is ASAP 2420 adsorber of Micromeritics company in the United States. The test conditions are: the sample is vacuum degassed at 100℃ and 300℃ for 0.5h and 6h respectively, and the N2 adsorption-desorption test is carried out at 77.4K temperature. The adsorption and desorption amounts of nitrogen under different specific pressure conditions are obtained, and the N2 adsorption-desorption isotherm curve is obtained. The BET specific surface area is calculated by BET formula, the micropore area is calculated by t-plot, and the pore size distribution is calculated by BJH.

[0088] The relative crystallinity of the sample is detected by X-ray diffraction method, the instrument is Empyrean. The test conditions are: tube voltage 40 kV, tube current 40 mA, Cu target Kα radiation, 2θ scanning range 5°-35°, scanning rate 2(°) / min.

[0089] Example 1

[0090] (1) Weigh 91.2 grams of tetraethyl orthosilicate, then add 639.14 grams of deionized water, and stir and heat in a water bath at 40°C for 2 hours. Then increase the water bath temperature to 70°C and stir and heat for 4 hours to remove ethanol produced by hydrolysis of the silicon source. In this process, water evaporated simultaneously with ethanol is supplemented intermittently to the system. Then mix the obtained mixed liquid with 111.65 grams of a tetrapropylammonium hydroxide aqueous solution (25.0% by mass) at 25°C for 1 hour to obtain a first mixed product;

[0091] (2) Weigh 3.44 grams of sodium hydroxide particles, add 60.8 grams of deionized water, and stir until the sodium hydroxide is completely dissolved. Then add 8.16 grams of aluminum nitrate nonahydrate, and stir at room temperature for 1.0 hour to obtain a second mixed product (i.e., an aluminum source solution);

[0092] (3) Slowly add the second mixed product to the first mixed product, and mix uniformly. Stir at room temperature for 4.0 hours. Then move the obtained precursor solution into a synthesis kettle, and dynamically crystallize at 170°C for 48 hours. After crystallization, centrifugal filtration, washing, and drying are performed, and then the first solid product I-M1 is obtained by calcining at 550°C for 4 hours;

[0093] (4) Mix the first solid product with a sodium hydroxide solution having a concentration of 0.65 mol / L uniformly, with a mass ratio of the first solid product to the alkali solution being 1:10. Then increase the temperature to 80°C at a rate of 2°C / min, and stir at this temperature for 30 minutes. After filtration, washing, and drying, a second solid product is obtained;

[0094] (5) Mix the second solid product, ammonium chloride, and deionized water uniformly according to a mass ratio of 1:1:10, and stir and heat in a water bath at 80°C for 30 minutes. After filtration, washing, and drying, mix the obtained dried solid, ammonium chloride, and deionized water uniformly according to a mass ratio of 1:0.5:10, and perform a second ammonium exchange. After filtration, washing, and drying, the hydrogen-type hollow multi-level pore ZSM-5 nanocrystal material I-S1-H is obtained by calcining at 550°C for 2 hours. Figure 1 FIG. 4 is a TEM image of the hydrogen-type hollow multi-level pore ZSM-5 nanocrystal material I-S1-H.

[0095] Example 2

[0096] (1) Weigh 60.0 grams of methyl orthosilicate, then add 425.0 grams of deionized water, and stir and heat in a water bath at 30°C for 5 hours. Then increase the water bath temperature to 70°C and stir and heat for 4 hours to remove ethanol produced by hydrolysis of the silicon source. In this process, water evaporated simultaneously with ethanol is supplemented intermittently to the system. Then mix the obtained mixed liquid with 34.5 grams of a tetrapropylammonium bromide aqueous solution (25.0% by mass) at 20°C for 0.5 hour to obtain a first mixed product;

[0097] (2) Weigh 1.30 grams of sodium hydroxide particles, add 31.0 grams of deionized water, and make the sodium hydroxide completely dissolved, then add 0.85 grams of sodium aluminate (alumina content is 62.0%), stir at room temperature for 2.0 hours, to obtain a second mixed product (i.e. aluminum source solution);

[0098] (3) Slowly add the second mixed product to the first mixed product, mix uniformly, and stir at room temperature for 4.0 hours; move the obtained precursor solution into a synthesis kettle, and dynamically crystallize at 180°C for 24 hours; after the crystallization is completed, centrifugal filtration, washing, and drying are performed, and calcination at 550°C for 4 hours is performed, to obtain a first solid product I-M2;

[0099] (4) Mix the first solid product and a sodium hydroxide solution with a concentration of 0.6 mol / L uniformly, the mass ratio of the first solid product to the alkali solution is 1:10, after a temperature increasing rate of 4°C / min is used to increase the temperature to 80°C, stirring at the temperature for 30 minutes is performed, and filtration, washing, and drying are performed, to obtain a second solid product;

[0100] (5) Mix the second solid product, ammonium chloride, and deionized water according to a mass ratio of 1:1:10 uniformly, and stir and heat in a water bath at 80°C for 30 minutes; perform filtration, washing, and drying, then mix the obtained dried solid, ammonium chloride, and deionized water according to a mass ratio of 1:0.5:10 uniformly, perform a second ammonium exchange, perform filtration, washing, and drying, and perform calcination at 550°C for 2 hours, to obtain a hydrogen type hollow multi-level pore ZSM-5 nanocrystal material, denoted as I-S2-H, Figure 2 is a TEM image thereof.

[0101] Example 3

[0102] (1) Weigh 65.13 grams of a tetrapropylammonium hydroxide aqueous solution (mass fraction is 25.0%), add 476.62 grams of deionized water, stir at room temperature for 10 minutes, then add 165.20 grams of silica sol (SiO2 content is 25%), and stir in a water bath at 50°C for 1.0 hour, to obtain a third mixed product; move the third mixed product into a reaction kettle, and crystallize at 80°C for 2 hours, then increase the temperature to 170°C, and crystallize for 12 hours, to obtain a fourth mixed product;

[0103] (2) Weigh 1.39 grams of sodium hydroxide particles, add 27.2 grams of deionized water, and make the sodium hydroxide completely dissolved, then add 4.76 grams of aluminum nitrate nonahydrate, and stir at room temperature for 1.0 hour, to obtain a fifth mixed product (i.e. aluminum source solution);

[0104] (3) Add the fifth mixed product of step 2 to the fourth mixed product, stir uniformly, and continue to crystallize at 170°C for 36 hours; after the crystallization is completed, perform centrifugal filtration, washing, and drying, and perform calcination at 550°C for 4 hours, to obtain a third solid product I-M3;

[0105] (4) The third solid product and a sodium hydroxide alkali solution with a concentration of 1.0 mol / L were uniformly mixed, the mass ratio of molecular sieve to alkali solution was 1:10, and the temperature was increased to 80°C at a rate of 5°C / min, then stirred at the temperature for 30 min, filtered, washed, and dried to obtain a fourth solid product;

[0106] (5) The fourth solid product, ammonium chloride, and deionized water were uniformly mixed according to a mass ratio of 1:1:10, and stirred and heated at 80°C for 30 min, then filtered, washed, and dried. The dried solid, ammonium chloride, and deionized water were uniformly mixed according to a mass ratio of 1:0.5:10, and subjected to a second ammonium exchange, then filtered, washed, and dried, and calcined at 550°C for 2 h to obtain a hydrogen-type hollow multi-level pore ZSM-5 nanocrystal material, denoted as I-S3-H, Figure 3 which is a TEM image thereof.

[0107] Example 4

[0108] (1) 134.4 g of tetraethyl orthosilicate was weighed, and 833.60 g of deionized water was added. After stirring and heating at 50°C for 1 h, the water bath temperature was increased to 80°C for stirring and heating for 3 h to remove ethanol produced by hydrolysis of the silicon source. During the process, water evaporated simultaneously with ethanol was supplemented to the system intermittently. The obtained mixed liquid was mixed and stirred with 65.13 g of a tetrapropylammonium hydroxide aqueous solution (25.0% by mass fraction) at 30°C for 1.5 h to obtain a first mixed product;

[0109] (2) 2.0 g of sodium hydroxide particles was weighed, and 26 g of deionized water was added to completely dissolve the sodium hydroxide. Then, 4.76 g of aluminum nitrate nonahydrate was added, and stirred at room temperature for 1.0 h to obtain a second mixed product (i.e., an aluminum source solution);

[0110] (3) The second mixed product was slowly added to the first mixed product, and uniformly mixed, and stirred at room temperature for 4.0 h. The obtained precursor solution was transferred into a synthesis kettle, and dynamically crystallized at 160°C for 60 h. After crystallization, centrifugal filtration, washing, and drying were performed, and calcination was performed at 550°C for 4 h to obtain a first solid product I-M4;

[0111] (4) The first solid product and a sodium hydroxide solution with a concentration of 0.7 mol / L were uniformly mixed, the mass ratio of molecular sieve to alkali solution was 1:10, and the temperature was increased to 80°C at a rate of 2°C / min, then stirred at the temperature for 30 min, filtered, washed, and dried to obtain a second solid product;

[0112] (5) The second solid product: ammonium chloride: deionized water was mixed uniformly at a mass ratio of 1:1:10, stirred and heated under 80℃ water bath for 30 min, filtered, washed, dried, and then the dried solid: ammonium chloride: deionized water was mixed uniformly at a mass ratio of 1:0.5:10, ammonium exchanged for the second time, filtered, washed, dried, and calcined at 550℃ for 2h to obtain the hydrogen-type hollow multi-level pore ZSM-5 nanocrystal material, recorded as I-S4-H, Figure 4 is a TEM image thereof.

[0113] Comparative Example 1

[0114] The ZSM-5 molecular sieve a of common crystal grains was purchased from Qilu Branch of Sinopec Catalyst Company, and the molar ratio of silicon and aluminum (SiO2 / Al2O3 was 50).

[0115] (1) The purchased ZSM-5 molecular sieve a and a sodium hydroxide solution with a concentration of 0.4 mol / L were mixed uniformly, the mass ratio of the ZSM-5 molecular sieve a to the alkali solution was 1:10, and the mixture was heated and stirred at 80℃ for 30 min, filtered, washed, and dried to obtain a second solid product.

[0116] (2) The purchased ZSM-5 molecular sieve a after alkali treatment: ammonium chloride: deionized water was mixed uniformly at a mass ratio of 1:1:10, stirred and heated under 80℃ water bath for 30 min, filtered, washed, dried, and then the dried solid: ammonium chloride: deionized water was mixed uniformly at a mass ratio of 1:0.5:10, ammonium exchanged for the second time, filtered, washed, dried, and calcined at 550℃ for 2h to obtain the hydrogen-type molecular sieve I-DS1-H.

[0117] Comparative Example 2

[0118] The ZSM-5 nanocrystal material was prepared by the same method as in Example 2, except that in step (1), 60.0 grams of methyl orthosilicate was weighed, and then 401.9 grams of deionized water was added, and the mixture was stirred and heated under 30℃ water bath for 5h; in step (2), 1.30 grams of sodium hydroxide particles was weighed, 54.1 grams of deionized water was added to dissolve the sodium hydroxide completely, and then 0.85 grams of sodium aluminate (aluminum oxide content was 62.0%) was added, and the mixture was stirred at room temperature for 2.0h to obtain a second mixed product (i.e. an aluminum source solution).

[0119] The obtained parent ZSM-5 molecular sieve was recorded as I-DM2, which was in the morphology of nanoclusters, Figure 6 is a TEM image thereof. The ZSM-5 material prepared after alkali treatment was recorded as I-DS2-H, which did not have a hollow structure, and was still a nanocluster ZSM-5 molecular sieve, Figure 7 is a TEM image thereof.

[0120] Comparative Example 3

[0121] The ZSM-5 nanocrystal material was prepared by the same method as in Example 2, except that in step (4), the first solid product was mixed with a sodium hydroxide solution having a concentration of 0.1 mol / L, the mass ratio of the first solid product to the alkali solution was 1:10, and the mixture was stirred at 80°C for 30 min. The second solid product was obtained by filtration, washing, and drying.

[0122] The prepared ZSM-5 nanocrystal material was recorded as I-DS3-H, which did not have a hollow structure.

[0123] Table 1

[0124]

[0125]

[0126]

[0127]

[0128]

[0129] In Table 1, R represents a template agent, and the ratio of the bulk phase silica-alumina molar ratio to the surface silica-alumina molar ratio represents the ratio of the bulk phase silica-alumina molar ratio to the surface silica-alumina molar ratio;

[0130] Mesopore specific surface area increase value = 100% x [mesopore specific surface area of the hollow hierarchical-pore ZSM-5 nanocrystal material / mesopore specific surface area of the first solid product (or the third solid product) - 1];

[0131] Mesopore specific volume increase value = 100% x [mesopore specific volume of the hollow hierarchical-pore ZSM-5 nanocrystal material / mesopore specific volume of the first solid product (or the third solid product) - 1];

[0132] Total acid amount increase value = 100% x [total acid amount of the hollow hierarchical-pore ZSM-5 nanocrystal material / total acid amount of the first solid product (or the third solid product) - 1].

[0133] Test Example 1

[0134] The molecular sieves prepared in the examples and the comparative examples were each hydrothermally treated at a temperature of 800°C for 17 hours to investigate the hydrothermal stability of the molecular sieves, and the evaluation results are shown in Table 2.

[0135] Table 2

[0136]

[0137]

[0138] Test Example 2

[0139] The ZSM-5 nanocrystalline materials prepared in the examples and comparative examples were evaluated on a fixed bed microreactor FB after hydrothermal treatment at a temperature of 800℃ for 17 hours, using monocyclic naphthene ethylcyclohexane as a model compound, to investigate the catalytic performance of the hollow hierarchical pore ZSM-5 nanocrystalline material after aging, the reaction temperature was 620℃, and the weight ratio of catalyst to oil was 3.0, and the evaluation results are shown in Table 3.

[0140] Table 3

[0141] Conversion, % Ethylene yield, % Propylene yield, % C4 olefin yield, % Example 1 77.49 6.72 15.08 10.57 Example 2 77.31 6.64 14.95 11.16 Example 3 76.15 6.57 14.05 10.03 Example 4 74.28 6.07 13.58 9.76 Comparative Example 1 65.18 4.79 9.85 7.46 Comparative Example 2 66.36 5.01 10.24 7.98 Comparative Example 3 68.15 5.26 11.61 8.15

[0142] As can be seen from the above table, the ZSM-5 nanocrystalline material with closed hollow hierarchical pores of the present application has excellent hydrothermal stability and catalytic performance, and can effectively improve the yield of ethylene, propylene and carbon four olefins.

[0143] The preferred embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0144] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combination manners.

[0145] Furthermore, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed content of the present application.

Claims

1. A ZSM-5 nanocrystalline material with hollow multi-level pores, the ZSM-5 nanocrystalline material having a closed hollow structure, the average grain size of the ZSM-5 nanocrystalline material being 0.2-3.0 μm, the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio being 1.0-1.5, the total specific surface area being 340-420 m 2 / g, the mesopore specific surface area being 40-150 m 2 / g, the N2 adsorption-desorption curve showing a H4 type hysteresis loop; and the micropore specific surface area being 190-380 m 2 / g.

2. The ZSM-5 nanocrystalline material of claim 1, wherein, The average grain size of the ZSM-5 nanocrystal material is 0.4-2.5 μm.

3. The ZSM-5 nanocrystalline material of claim 1, wherein, The ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the ZSM-5 nanocrystal material is 1.0-1.

3.

4. The ZSM-5 nanocrystalline material of claim 1, wherein, The total specific surface area of the ZSM-5 nanocrystal material is 360-400 m 2 / g; the mesopore specific surface area is 50-140 m 2 / g; and the micropore specific surface area is 190-360 m 2 / g.

5. The ZSM-5 nanocrystalline material of claim 1, wherein, The relative crystallinity of the ZSM-5 nanocrystal material is 75-95%.

6. A method for preparing the ZSM-5 nanocrystal material according to any one of claims 1-5, comprising: (1) mixing and stirring a first organic silicon source and a first solvent at 30-50°C for 0.5-5 hours, then increasing the temperature to 70-100°C and mixing and stirring for 2-10 hours, mixing the obtained mixed liquid with a first template agent at 20-30°C for 0.5-3.0 hours to obtain a first mixed product; (2) mixing a first alkali metal hydroxide in terms of alkali metal oxide, a second solvent and a first aluminum source in terms of Al2O3 in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain a second mixed product; (3) mixing the first mixed product with the second mixed product and then performing dynamic crystallization, taking out the obtained solid and performing a first calcination to obtain a first solid product; The conditions of the dynamic crystallization include a temperature of 160-180°C and a time of 12-60 hours; (4) mixing the first solid product with a first solution containing alkali in a weight ratio of 1:(2-10), increasing the temperature to a reaction temperature at a temperature increasing rate of 1-5°C / min, and then reacting at the reaction temperature for 10-90 min to obtain a second solid product; wherein the reaction temperature is 60-90°C, the content of alkali in the first solution containing alkali is 0.45-2 mol / L, and the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the first solid product is 1.2-5.0; (5) performing a first ammonium exchange on the second solid product, and optionally performing a third calcination to obtain a ZSM-5 nanocrystal material with hollow hierarchical pores; wherein the total amount of the first template agent, the first solvent and the second solvent, and the molar ratio of the amount of the first alkali metal hydroxide to the amount of the first organic silicon source are (0.06-0.55):(10-100):(0.02-1.5):1, and the molar ratio of the amount of the first organic silicon source to the amount of the first aluminum source is (20-500):1; wherein the first organic silicon source is in terms of SiO2, the first alkali metal hydroxide is in terms of alkali metal oxide, and the first aluminum source is in terms of Al2O3; or the method comprises: S1, mixing a second template agent, a second inorganic silicon source and a third solvent at 30-50°C for 0.5-3.0 hours, and then performing a first hydrothermal treatment and a second hydrothermal treatment on the obtained third mixed product in sequence to obtain a fourth mixed product; wherein the conditions of the first hydrothermal treatment include a temperature of 80-150°C and a time of 1-6 hours; and the conditions of the second hydrothermal treatment include a temperature of 160-180°C and a time of 12-260 hours; S2, mixing the second alkali hydroxide calculated as alkali metal oxide, the fourth solvent and the second aluminum source calculated as Al2O3 in a molar ratio of (1.5-5):(60-350):1 at 20-80℃ for 0.5-2.0 hours to obtain a fifth mixed product; S3, mixing the fourth mixed product and the fifth mixed product, and performing third hydrothermal treatment on the obtained mixture, taking out the obtained solid and performing second calcination to obtain a third solid product; the third hydrothermal treatment has a temperature of 160-180℃ and a time of 12-60 hours; S4, mixing the third solid product and the second solution containing alkali in a weight ratio of 1:(2-10) to obtain a fourth solid product by increasing the temperature to the reaction temperature at a temperature increasing rate of 1-5℃ / min and then reacting at the reaction temperature for 10-90min; wherein the reaction temperature is 60-90℃, the content of alkali in the second solution containing alkali is 0.45-2mol / L, and the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the third solid product is 1.2-5.0; S5, performing second ammonium exchange on the fourth solid product, and optionally performing fourth calcination to obtain a ZSM-5 nanocrystalline material with hollow hierarchical pores; The molar ratio of the amount of the second template agent, the third solvent, the second alkali hydroxide and the second inorganic silicon source is (0.06-0.55):(10-100):(0.02-1.5):1, and the molar ratio of the second inorganic silicon source to the second aluminum source is (20-500):1; wherein the second inorganic silicon source is calculated as SiO2, the second alkali hydroxide is calculated as alkali metal oxide, and the second aluminum source is calculated as Al2O3.

7. The method of claim 6, wherein, In step (2), the molar ratio of the amount of the first alkali hydroxide calculated as alkali metal oxide, the second solvent and the first aluminum source calculated as Al2O3 is (2-4.5):(80-350):

1. In step S2, the molar ratio of the amount of the second alkali hydroxide calculated as alkali metal oxide, the fourth solvent and the second aluminum source calculated as Al2O3 is (2-4.5):(80-350):

1.

8. The method of claim 6, wherein, The first organic silicon source is selected from one or more of methyl orthosilicate and ethyl orthosilicate; The second inorganic silicon source is selected from one or more of silica sol, water glass and solid silica gel; The first template agent and the second template agent are each independently selected from one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine and hexanediamine; The first aluminum source and the second aluminum source are each independently selected from one or more of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum isopropyl alcohol and aluminum sol; The first alkali hydroxide and the second alkali hydroxide are each independently selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; The first solution containing alkali and the second solution containing alkali are each independently selected from one or more of sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide and barium hydroxide.

9. The method of claim 6, wherein, The conditions of the first calcination and the second calcination each independently include: temperature of 400-600℃, time of 2-6 hours.

10. The method of claim 6, wherein, In step (5), the first ammonium exchange of the second solid product includes: mixing the second solid product, a first ammonium source and a fifth solvent in a weight ratio of 1: (0.5-1.0): (8-10), and then reacting the obtained mixture at 70-90℃ for 0.5-5 hours; In step S5, the second ammonium exchange of the fourth solid product includes: mixing the fourth solid product, a second ammonium source and a sixth solvent in a weight ratio of 1: (0.5-1.0): (8-10), and then reacting the obtained mixture at 70-90℃ for 0.5-2 hours; The first ammonium source and the second ammonium source are each independently selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

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