Zsm-5 molecular sieve, its preparation method and application, method for catalytic cracking of triisopropylbenzene

Abstract

The application relates to the field of molecular sieves, and discloses a ZSM-5 molecular sieve, a preparation method and application thereof, and a catalytic cracking method of triisopropylbenzene. The ZSM-5 molecular sieve has a cross-assembled aggregate crystal morphology formed by sheet-shaped nanocrystals, and the sheet-shaped nanocrystals adjacent to each other in the molecular sieve have a cross-assembled aggregate crystal morphology formed by 90 DEG + / -10 DEG rotation symbiosis and 30 DEG + / -5 DEG rotation symbiosis.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve technology, specifically to a ZSM-5 molecular sieve, its preparation method and application, and a catalytic cracking method for triisopropylbenzene. Background Technology

[0002] ZSM-5 molecular sieves with MFI structure have a three-dimensional channel structure, with smaller pore sizes along the zigzag channel along the a-axis. The straight channel along the b-axis is larger. Therefore, the diffusion rate of molecules differs within different pores, and shortening the b-axis can effectively mitigate the impact of diffusion resistance on catalytic performance. Ryoo et al. synthesized MFI zeolite nanosheets using amphiphilic structure-directing agents, introducing mesopores / macropores, which greatly improved diffusion performance and acid site accessibility [RyongRyoo et al., Science, 333(6040); RyongRyoo et al., Chem. Mater., 2011, 23, 5131-5137]. However, the use of amphiphilic structure-directing agents leads to a reduction in the zeolite acid concentration range, often making it impossible to synthesize molecular sieves with higher Si / Al ratios. Furthermore, problems exist such as high cost of structure-directing agents, low crystallinity of molecular sieves, low acid strength and hydrothermal stability, and low synthesis yield.

[0003] Xiao and Rimer et al. synthesized nanosheet ZSM-5 molecular sieves using small molecule quaternary ammonium salt template agents and template-free methods, respectively. However, the narrow silica-alumina ratio window and the difficulty in controlling acidity in catalytic applications still exist [Feng-ShouXiao et al., J.Am.Chem.Soc., 2022, 144, 14, 6270-6277; Jeffrey D.Rimer et al., Adv.Mater., 2021, 33, 2100897]. Summary of the Invention

[0004] The purpose of this invention is to overcome the mass transfer difficulties of existing ZSM-5 molecular sieves, such as their poor catalytic performance in organic conversion reactions, and to provide a ZSM-5 molecular sieve, its preparation method and application, and a method for the catalytic cracking of triisopropylbenzene. This ZSM-5 molecular sieve has good accessibility and exhibits good catalytic performance when used in organic conversion reactions, such as the catalytic cracking of triisopropylbenzene.

[0005] In order to achieve the above object, the present application provides a ZSM-5 molecular sieve in a first aspect, wherein the ZSM-5 molecular sieve has a morphology of agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals, and the morphology of the agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve.

[0006] The present application provides a preparation method of the ZSM-5 molecular sieve in the first aspect in a second aspect, wherein the preparation method comprises: performing crystallization treatment on a raw material mixture solution containing a silicon source in the presence of a structure directing agent, wherein the structure directing agent contains a structural unit a represented by formula (1),

[0007]

[0008] In formula (1), X is a halogen ion or a hydroxyl ion, and * represents a connection site.

[0009] The present application provides an application of the ZSM-5 molecular sieve in the first aspect in a third aspect in adsorption treatment and / or organic compound conversion reaction.

[0010] The present application provides a method for catalytic cracking of triisopropylbenzene in a fourth aspect, wherein the method comprises: performing catalytic cracking reaction of triisopropylbenzene in the presence of the ZSM-5 molecular sieve in the first aspect and / or the hydrogen type ZSM-5 molecular sieve after modification of the ZSM-5 molecular sieve in the first aspect as an active component.

[0011] Compared with the prior art, the present application has at least the following beneficial effects:

[0012] The ZSM-5 molecular sieve in the present application has the morphology of agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals, which has a special crystal morphology, good accessibility, good catalytic performance in organic conversion reaction, high specific surface area, and a wide range of silicon-aluminum ratio. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is an X-ray diffraction pattern of the molecular sieve sample in Example 1;

[0014] Figure 2 is an N2 physical adsorption graph of the molecular sieve sample in Example 1;

[0015] Figure 3 is an X-ray diffraction pattern of the molecular sieve sample in Example 2;

[0016] Figure 4is an X-ray diffraction pattern of a molecular sieve sample in Example 3;

[0017] Figure 5 is an SEM image of a molecular sieve sample in Example 3;

[0018] Figure 6 is an X-ray diffraction pattern of a molecular sieve sample in Example 4;

[0019] Figure 7 is an X-ray diffraction pattern of a molecular sieve sample in Example 5;

[0020] Figure 8 is an SEM image of a molecular sieve sample in Example 5;

[0021] Figure 9 is an SEM image of a molecular sieve sample of a molecular sieve sample in Comparative Example 1;

[0022] Figure 10 is an SEM image of a molecular sieve sample of a molecular sieve sample in Comparative Example 2. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values claimed herein are presented only as approximations. The ranges and values are understood to include values approximating the stated ranges and values. For example, a range of "1 to 5" is intended to include any number between (and the integers) 1 and 5. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include any sub-range of the same, such as for example 1 to 6, 5.1 to 5.9, and so forth.

[0024] The first aspect of the present application provides a ZSM-5 molecular sieve, wherein the ZSM-5 molecular sieve has a morphology of agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals, and the morphology of the agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve.

[0025] In the present application, the morphology of the agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve is special, has good accessibility, can be beneficial to the diffusion of raw materials and their products, and has good catalytic performance for organic conversion reactions.

[0026] According to the present application, in some preferred embodiments, the proportion of the morphology of the agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve is greater than or equal to 80%, preferably 80-100%. By using the foregoing embodiments, the diffusion of molecules is more beneficial when the molecular sieve is used.

[0027] In the present application, the structure of the ZSM-5 molecular sieve cross-assembled by sheet-shaped nanocrystals is determined by X-ray diffraction spectrum (XRD), and the X-ray diffraction spectrum (XRD) is determined by an X-ray powder diffractometer. Before sample testing, a scanning electron microscope (SEM) is used to observe the crystallization of the molecular sieve sample, to confirm that only one crystal is contained in the sample, i.e., the molecular sieve sample is a pure phase, and on this basis, XRD testing is performed, to ensure that there is no interference peak of other crystals in the diffraction peak in the XRD spectrum; during testing, the X-ray powder diffractometer for the molecular sieve is a D / MAX 2550VB / PC type X-ray powder diffractometer of Japan Rigaku Company, CuKα ray source is used to analyze the phase of the sample, and the scanning range is 5-50°. The nickel filter is scanned at 5-50°, the operating voltage is 40KV, the current is 20mA, and the scanning rate is 10° / min.

[0028] According to the present application, in some embodiments, the size of the agglomerated crystal is 0.5-3.0 μm, for example, 0.5 μm, 0.6 μm, 0.8 μm, 0.9 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.9 μm, 2.1 μm, 2.5 μm or 3.0 μm, preferably 0.6-2.5 μm. With the foregoing embodiments, the molecular sieve is more beneficial to the diffusion of molecules when used, and the molecular sieve structure has better stability.

[0029] According to the present application, in some embodiments, the aspect ratio of the sheet-shaped nanocrystal is 1.2-2.5, for example, 1.2, 1.5, 1.6, 1.7, 1.9, 2.0, 2.1, 2.3 or 2.5, preferably 1.2-2.0. With the foregoing embodiments, the molecular sieve has good diffusivity.

[0030] According to the present application, in some embodiments, the length-thickness ratio of the sheet-shaped nanocrystal is 4-20, for example, 4, 5, 5.6, 6.6, 7.3, 8, 8.3, 8.5, 9, 10, 11, 12, 13.8, 14.4, 15, 16, 17, 18, 19 or 20, preferably 4-15. With the foregoing embodiments, the molecular sieve has good diffusion performance and can exhibit high adsorption and catalytic performance.

[0031] According to the present application, the length of the platelet-shaped nanocrystal is not particularly limited as long as the object of the present application can be achieved, and in some preferred embodiments, the length of the platelet-shaped nanocrystal is 30-2500 nm, such as 30 nm, 50 nm, 60 nm, 70 nm, 78 nm, 165 nm, 230 nm, 350 nm, 450 nm, 620 nm, 640 nm, 1000 nm, 1500 nm, 1800 nm, 2000 nm, 2200 nm or 2500 nm, preferably 30-2200 nm. With the foregoing preferred embodiments, the molecular sieve has better diffusivity.

[0032] According to the present application, the width of the platelet-shaped nanocrystal is not particularly limited as long as the object of the present application can be achieved, and in some preferred embodiments, the width of the platelet-shaped nanocrystal is 20-1500 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 110 nm, 120 nm, 200 nm, 230 nm, 330 nm, 370 nm, 500 nm, 600 nm, 800 nm, 1000 nm, 1100 nm, 1300 nm, 1400 nm or 1500 nm, preferably 20-1300 nm. With the foregoing preferred embodiments, the molecular sieve has better diffusivity.

[0033] According to the present application, the thickness of the platelet-shaped nanocrystal is not particularly limited as long as the object of the present application can be achieved, and in some preferred embodiments, the thickness of the platelet-shaped nanocrystal is 5-150 nm, such as 5 nm, 8 nm, 10 nm, 14 nm, 15 nm, 16 nm, 25 nm, 40 nm, 75 nm, 80 nm, 100 nm, 120 nm, 130 nm, 140 nm or 150 nm, preferably 8-130 nm. With the foregoing preferred embodiments, the molecular sieve has better diffusivity.

[0034] In the present application, the morphology and size of the sheet-like nanocrystals and the agglomerated crystals can be observed from the scanning electron microscope (SEM) image of the molecular sieve. In the present application, the scanning electron microscope (SEM) used is a field emission scanning electron microscope of NOVA NanoSEM 450 type from FEI Company, USA. When scanning, the molecular sieve is observed under a certain magnification of the scanning electron microscope, a random observation field is selected, the average value of the length of all sheet-like nanocrystals in the observation field is calculated, the operation is repeated for 10 times, and the average value of the sum of 10 times is taken as the length of the sheet-like nanocrystal. The width and thickness of all crystals in the observation field are measured in the same way, and the length of the agglomerated crystal is taken as the size of the agglomerated crystal. The operation is repeated for 5 times. The proportion of the agglomerated crystal morphology formed by the cross-assembly of the sheet-like nanocrystals rotated at 90°±10° and the sheet-like nanocrystals rotated at 30°±5° in the total statistical number is calculated, i.e. the proportion of the agglomerated crystal morphology formed by the cross-assembly of the sheet-like nanocrystals rotated at 90°±10° and the sheet-like nanocrystals rotated at 30°±5° in the total statistical number is calculated, and the operation is repeated for 5 times.

[0035] According to the present application, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is not particularly limited as long as the purpose of the present application can be achieved. In some embodiments, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is greater than or equal to 20. The molecular sieve in the foregoing embodiments has good diffusion performance and a wide silicon-aluminum ratio window, and can be used as an adsorbent or a catalyst for organic compound conversion.

[0036] In the present application, it can be understood that the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve in the present application can be infinite. When it is infinite, it means that the ZSM-5 molecular sieve is a pure-silicon ZSM-5 molecular sieve, i.e. a Silicalite-1 molecular sieve.

[0037] In the present application, the inductively coupled plasma atomic emission spectrometer (ICP) used for the molecular sieve is a Varian710-ES, and the content of elements is detected by dissolving the sample with hydrofluoric acid in moles. When the SiO2 / Al2O3 molar ratio is greater than 1500, the molecular sieve is considered to be composed of pure silicon.

[0038] According to the present application, in some embodiments, the total specific surface area of the ZSM-5 molecular sieve is not less than 450 m2 / g. The molecular sieve in the foregoing embodiments has good molecular diffusion. 2

[0039] According to the present application, in some preferred embodiments, the total specific surface area of the ZSM-5 molecular sieve is 450-700 m2 / g. The molecular sieve in the foregoing embodiments has good molecular diffusion. 2 ​​

[0040] According to the present application, in some embodiments, the external specific surface area of the ZSM-5 molecular sieve is not less than 60 m2 / g. 2 The molecular sieve in the foregoing embodiments has good diffusivity and stability.

[0041] According to the present application, in some preferred embodiments, the external specific surface area of the ZSM-5 molecular sieve is 60-200 m2 / g. 2 The molecular sieve in the foregoing embodiments has good diffusivity and stability.

[0042] According to the present application, the total pore volume of the ZSM-5 molecular sieve is not particularly limited as long as the purpose of the present application can be achieved, and in some embodiments, the total pore volume of the ZSM-5 molecular sieve is not less than 0.35 cm3 / g. 3 The molecular sieve in the foregoing embodiments has good diffusivity and adsorptivity.

[0043] According to the present application, in some preferred embodiments, the total pore volume of the ZSM-5 molecular sieve is 0.35-0.60 cm3 / g. 3 The molecular sieve in the foregoing embodiments has good diffusivity and adsorptivity.

[0044] According to the present application, in some embodiments, the micropore volume of the ZSM-5 molecular sieve is not less than 0.12 cm3 / g. 3 The molecular sieve in the foregoing embodiments has good diffusivity and adsorptivity.

[0045] According to the present application, in some preferred embodiments, the micropore volume of the ZSM-5 molecular sieve is 0.12-0.24 cm3 / g. 3 The molecular sieve in the foregoing embodiments has good diffusivity and adsorptivity.

[0046] In the present application, the total specific surface area, external specific surface area, total pore volume and micropore volume of the molecular sieve are measured by nitrogen physical adsorption-desorption method (BET method): the nitrogen physical adsorption-desorption isotherm of the molecular sieve is measured by using a physical adsorption instrument (3H-2000PS4 specific surface and pore size analyzer), and then calculated by BET equation and t-plot equation. The experimental conditions for the molecular sieve are as follows: measurement temperature -196℃, and the molecular sieve is heat-treated in air atmosphere at 550℃ for 6 hours and then pretreated in vacuum at 350℃ for 4 hours before measurement.

[0047] The present application provides a preparation method of the ZSM-5 molecular sieve according to the first aspect of the present application, wherein the preparation method comprises: performing crystallization treatment on a raw material mixture containing a silicon source in the presence of a structure directing agent,

[0048] The structure directing agent contains structural unit a shown in formula (1),

[0049]

[0050] In formula (1), X is halogen ion or hydroxyl ion, and * represents a connection site.

[0051] In the present application, the use of the polymer containing structural unit a shown in formula (1) as the structure directing agent can make the molecular sieve have a special morphology of agglomerate crystals formed by cross assembly of sheet-shaped nanocrystals, and the molecular sieve has good diffusion performance.

[0052] According to the present application, it can be understood that the structure directing agent containing structural unit a shown in formula (1) is a polymer, and the polymer usually exists in the form of a mixture, i.e., a mixture of structure directing agents containing different polymerization degrees (i.e., different numbers of structural unit a) of the same structural unit a. In the present application, the average polymerization degree of structural unit a refers to the average number of structural unit a, and in some embodiments, the average polymerization degree of the structure directing agent is 2-20, such as 2, 3.9, 5.2, 6, 7, 8, 9.7, 11, 12, 13, 15, 18 or 20, preferably 3-12. By using the foregoing embodiments, the molecular sieve with a special morphology can be prepared, and the molecular sieve has good molecular diffusion performance.

[0053] In the present application, [Pr4-6-6-(Y)2] n represents the structure of the structure directing agent (SDA), wherein Y is OH or halogen, and n is the average polymerization degree. The amount of the structure directing agent in the raw material system is the total molar amount of structural unit a.

[0054] According to the present application, as long as the purpose of the present application can be achieved, the amount of the silicon source is not particularly limited, and in some embodiments, the molar ratio of the silicon source to the structure directing agent is 1:(0.1-0.4), such as 1:0.1, 1:0.16, 1:0.21, 1:0.28 or 1:0.3, in terms of the molar amount of SiO2 provided by the silicon source and the molar amount of structural unit a of the structure directing agent. By using the foregoing embodiments, the molecular sieve prepared has good diffusion performance.

[0055] According to the present application, it can be understood that the raw material mixture is obtained by mixing raw materials including a silicon source with a solvent, and as long as the purpose of the present application can be achieved, the amount of the solvent added is not particularly limited, and in some embodiments, the molar ratio of the silicon source to the solvent in the raw material mixture is 1:(15-180), in terms of the molar amount of SiO2 provided by the silicon source and the molar amount of the solvent.

[0056] According to the present application, the type of the solvent is not particularly limited as long as the object of the present application can be achieved, and water is exemplarily used as the solvent in the present application to illustrate the advantages of the present application, but the present application is not limited thereto.

[0057] According to the present application, the silicon source is a raw material capable of providing silicon dioxide, and the specific type of the silicon source is not particularly limited as long as the object of the present application can be achieved, and in some embodiments, the silicon source is selected from at least one of tetraethyl orthosilicate, fumed silica, silica sol and white carbon black.

[0058] According to the present application, in some embodiments, the raw material mixture further contains an optional aluminum source.

[0059] According to the present application, it can be understood that in some other embodiments, no aluminum source is used in the preparation of the ZSM-5 molecular sieve according to the present application, and in this case, the ZSM-5 molecular sieve obtained is a pure silicon molecular sieve.

[0060] According to the present application, when an aluminum source is used in the preparation of the ZSM-5 molecular sieve according to the present application (i.e. when the raw material mixture contains an aluminum source), the amount of the aluminum source is not particularly limited as long as the object of the present application can be achieved, and in some embodiments, the molar ratio of the silicon source to the aluminum source is 1:(0-0.05) and is not 0, the molar amount of the silicon source being calculated based on the amount of SiO2 provided, and the molar amount of the aluminum source being calculated based on the amount of Al2O3 provided. By using the foregoing embodiment, a wider window of the silicon to aluminum ratio can be obtained.

[0061] According to the present application, when an aluminum source is used in the preparation of the ZSM-5 molecular sieve according to the present application (i.e. when the raw material mixture contains an aluminum source), the specific type of the optional aluminum source can be selected by those skilled in the art according to the need, and in some embodiments, the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum hydroxide, sodium metaaluminate, pseudo-boehmite and aluminum isopropoxide.

[0062] According to the present application, in some embodiments, the raw material mixture further contains an optional alkali source.

[0063] According to the present application, it can be understood that in some other embodiments, no alkali source is used in the preparation of the ZSM-5 molecular sieve according to the present application. When no alkali source is used, the generation of a large amount of waste liquid during the modification (e.g. hydrogen modification) of the ZSM-5 molecular sieve obtained can be avoided.

[0064] According to the present application, when the alkali source is used in the preparation of the ZSM-5 molecular sieve (i.e. when the raw material mixture contains the alkali source), the amount of the alkali source is not particularly limited as long as the purpose of the present application can be achieved, and in some embodiments, the molar ratio of the silicon source to the alkali source is 1:(0-0.3) in terms of the molar amount of SiO2 provided by the silicon source and the molar amount of cations provided by the alkali source, and is not 0.

[0065] According to the present application, when the alkali source is used in the preparation of the ZSM-5 molecular sieve (i.e. when the raw material mixture contains the alkali source), the specific type of the optional alkali source can be selected by those skilled in the art according to the needs, and in some embodiments, the alkali source is selected from at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.

[0066] According to the present application, the conditions of the crystallization treatment are not particularly limited as long as the purpose of the present application can be achieved, and in some embodiments, the conditions of the crystallization treatment include that the crystallization temperature is 120-190°C, preferably 140-180°C. With the foregoing embodiments, the molecular sieve prepared has a special morphology and good diffusivity.

[0067] According to the present application, in some embodiments, the conditions of the crystallization treatment include that the crystallization time is 2-15 days, preferably 3-14 days. With the foregoing embodiments, the molecular sieve prepared has a special morphology and good diffusivity.

[0068] According to the present application, the crystallization treatment can be carried out under static conditions or under dynamic conditions as long as the purpose of the present application can be achieved, and in the present application, the advantages of the present application are exemplarily illustrated under static conditions, but the present application is not limited thereto.

[0069] According to the present application, in some embodiments, the method for preparing the ZSM-5 molecular sieve further includes separation and calcination after the crystallization treatment.

[0070] According to the present application, the separation after the crystallization treatment is to obtain the molecular sieve product, which can be obtained by any separation method in the art, such as a separation method of filtering, washing and drying the mixture obtained after the crystallization. Among them, the filtering, washing and drying can be carried out in any manner in the art. For example, when filtering, a simple suction filtration in the art can be used to obtain the product mixture; when washing, deionized water and / or ethanol can be used for washing; and when drying, it can be carried out under normal pressure or under reduced pressure, and those skilled in the art can select appropriate drying time and drying temperature according to the needs, for example, the drying temperature is 40-250°C, preferably 60-150°C, and the drying time is 8-30 hours, preferably 10-20 hours.

[0071] According to the present application, it is understood by those skilled in the art that when the raw material for preparing the ZSM-5 molecular sieve does not contain alkali metal ions, the ZSM-5 molecular sieve prepared by calcination after the end of the crystallization treatment is a hydrogen type ZSM-5 molecular sieve; when the raw material for preparing the ZSM-5 molecular sieve contains alkali metal ions, the ZSM-5 molecular sieve prepared by calcination after the end of the crystallization treatment is an alkali type molecular sieve (for example, a sodium type ZSM-5 molecular sieve, a potassium type ZSM-5 molecular sieve or a lithium type ZSM-5 molecular sieve), wherein the calcination can be carried out in any manner known in the art, and in some embodiments, the conditions for calcination include: being carried out in an oxygen-containing atmosphere, wherein the oxygen-containing atmosphere that can be listed includes an oxygen atmosphere or an air atmosphere; in some embodiments, the conditions for calcination include: a calcination temperature of 300-800°C, preferably 400-650°C; in some embodiments, the conditions for calcination include: a calcination time of 1-10 hours, preferably 3-6 hours.

[0072] The third aspect of the present application provides the use of the ZSM-5 molecular sieve according to the first aspect of the present application in adsorption treatment and / or organic compound conversion reactions.

[0073] In the present application, the ZSM-5 molecular sieve with specific morphology has high adsorption capacity and use stability for organic molecules, and has good catalytic performance in organic compound conversion reactions.

[0074] According to the present application, the ZSM-5 molecular sieve in the present application can be involved in any method of organic compound conversion reaction, and in some preferred embodiments, the organic compound conversion reaction includes isomerization of olefins, catalytic cracking of one or more of cumene, diisopropylbenzene, triisopropylbenzene and Beckmann rearrangement of cyclohexanone oxime to caprolactam.

[0075] In the present application, those skilled in the art can select pure silicon type ZSM-5 molecular sieve or silicon-aluminum type ZSM-5 molecular sieve for application as needed, for example, using pure silicon type ZSM-5 molecular sieve for Beckmann rearrangement to caprolactam, or using silicon-aluminum type ZSM-5 molecular sieve for catalytic cracking of cumene, diisopropylbenzene, triisopropylbenzene.

[0076] In the present application, the form of the ZSM-5 molecular sieve in use can be selected by those skilled in the art as needed, in some embodiments, the ZSM-5 molecular sieve can be used in any physical form, such as powder, granules, or prepared into a molded product (such as a strip, a clover, etc.) using a binder, which can be obtained in any manner known in the art and is not particularly limited; in other embodiments, the ZSM-5 molecular sieve can be modified according to the methods known in the art before use, for example, when the ZSM-5 molecular sieve is a basic molecular sieve (such as a sodium-type ZSM-5 molecular sieve, a potassium-type ZSM-5 molecular sieve, or a lithium-type ZSM-5 molecular sieve), the ZSM-5 molecular sieve can be modified into a hydrogen type to obtain a hydrogen-type ZSM-5 molecular sieve, which is used in the form of a hydrogen-type ZSM-5 molecular sieve.

[0077] According to the present application, the basic molecular sieve (such as a sodium-type ZSM-5 molecular sieve, a potassium-type ZSM-5 molecular sieve, or a lithium-type ZSM-5 molecular sieve) can be modified into a hydrogen type using the methods known in the art, in some embodiments, the basic molecular sieve is ammonium exchanged by an ammonium salt solution, and then washed, dried, and calcined to obtain a hydrogen-type ZSM-5 molecular sieve.

[0078] In the present application, the ammonium salt solution refers to a solution obtained by mixing an ammonium salt with water.

[0079] According to the present application, in some embodiments, the ammonium salt in the ammonium salt solution is selected from at least one of ammonium chloride, ammonium nitrate, ammonium carbonate, and ammonium sulfate.

[0080] According to the present application, in some embodiments, the concentration of the ammonium ion in the ammonium salt solution is 0.1-1.0 mol / L.

[0081] According to the present application, in some embodiments, the solid-liquid ratio (mass ratio) of the basic molecular sieve (such as a sodium-type ZSM-5 molecular sieve, a potassium-type ZSM-5 molecular sieve, or a lithium-type ZSM-5 molecular sieve) to the ammonium salt solution is 1:(5-20).

[0082] According to the present application, the number of times of ammonium exchange can be selected as needed, which is generally greater than or equal to 1 time; the conditions of ammonium exchange are not particularly limited, for example, the ammonium ion exchange is performed at 55-75°C for 1-5 hours.

[0083] According to the present application, after the ammonium exchange, the washing, drying, and calcination are performed, wherein the washing is a washing manner known in the art, such as centrifugal washing; the drying manner can be selected from the drying manners known in the art, such as overnight drying at 90-110°C; the calcination manner can be selected from the calcination manners known in the art, such as calcination in air at 500-600°C for 3-6 hours.

[0084] In the present application, the time of "overnight drying" is 10-16 hours.

[0085] The fourth aspect of the present application provides a method for catalytic cracking of cumene, wherein the method comprises: catalytic cracking of cumene in the presence of the ZSM-5 molecular sieve of the first aspect of the present application and / or the hydrogen type ZSM-5 molecular sieve after modification of the ZSM-5 molecular sieve of the first aspect of the present application.

[0086] In the present application, the ZSM-5 molecular sieve and / or the hydrogen type ZSM-5 molecular sieve after modification of the ZSM-5 molecular sieve of the present application has better conversion rate of cumene and better selectivity of product benzene when used for catalytic cracking of cumene.

[0087] According to the present application, the conditions of the catalytic cracking reaction are not particularly limited as long as the purpose of the present application can be achieved, and in some embodiments, the conditions of the catalytic cracking reaction comprise: the reaction temperature is 270-350℃.

[0088] According to the present application, in some embodiments, the conditions of the catalytic cracking reaction comprise: the weight hourly space velocity of cumene is 3-6h -1 .

[0089] According to the present application, the reaction time of the catalytic cracking reaction can be selected as needed, for example, 8-20h.

[0090] The present application will be described in detail below by way of examples. In the following examples and comparative examples:

[0091] The method for catalytic cracking of cumene is: under the action of a catalyst, cumene is subjected to a catalytic cracking reaction, and the conditions of the catalytic cracking reaction are: the reaction temperature is 270-350℃, the space velocity is 3-6h -1 , and the reaction time is 10-15h.

[0092] The conversion rate of cumene is calculated by the following formula: % of conversion rate of cumene = (molar amount of feed cumene - molar amount of cumene in product) / (molar amount of feed cumene) x 100%.

[0093] The selectivity of benzene is calculated by the following formula: % of selectivity of benzene = (molar amount of benzene in product) / (total molar amount of aromatic hydrocarbons in product) x 100%; wherein, the aromatic hydrocarbons in the product do not include the raw material cumene.

[0094] The method for Beckmann rearrangement of cyclohexanone oxime to caprolactam is: under the action of a catalyst, cyclohexanone is subjected to a Beckmann rearrangement reaction in a solvent, and the reaction conditions are: pure silicon ZSM-5 molecular sieve is used as the catalyst, 5wt% cyclohexanone oxime-ethanol solution, the reaction temperature is 300-400℃, and the space velocity is 3-6h -1 .

[0095] Conversion % of cyclohexanone oxime = (molar amount of cyclohexanone oxime in feed - molar amount of cyclohexanone oxime in product) / (molar amount of cyclohexanone oxime in feed) x 100%.

[0096] Selectivity % of caprolactam = (mass of caprolactam in product) / (total mass of product) x 100%; wherein the unreacted cyclohexanone oxime and solvent ethanol in raw materials in the product are not considered.

[0097] Example 1

[0098] A mixture was prepared by stirring 13.50 g of deionized water, 0.42 g of [Pr4-6-6-(OH)2] SDA, 0.008 g of sodium metaaluminate, 1.04 g of tetraethyl orthosilicate at room temperature for 24 hours, and the molar ratio of the final mixture was as follows: 3.9

[0099] SiO2 / Al2O3 = 102;

[0100] NaOH / SiO2 = 0.02;

[0101] SDA / SiO2 = 0.21;

[0102] H2O / SiO2 = 150;

[0103] The mixture was loaded into a stainless steel autoclave, and the crystallization was carried out at 165°C under static crystallization conditions for 13 days. After the crystallization was completed, the mixture was filtered, washed with water, and dried in an oven at 100°C overnight. The molecular sieve sample was obtained after calcination of the dried mixture in air at 550°C for 6 hours.

[0104] Figure 1 The X-ray diffraction pattern of the molecular sieve sample is shown in FIG. 1. Figure 1 It can be seen from the X-ray diffraction pattern that the molecular sieve sample is a ZSM-5 molecular sieve.

[0105] It can be seen from the SEM image of the molecular sieve sample that the molecular sieve sample has a morphology of agglomerated crystals formed by cross-assembly of sheet-shaped nanocrystals, and the proportion of the morphology of agglomerated crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation and 30°±5° rotation between adjacent sheet-shaped nanocrystals in the molecular sieve sample is 84%. The thickness of the sheet-shaped nanocrystals is 10 nm, the length is 50 nm, the width is 30 nm, the length-thickness ratio is 5, the length-width ratio is 1.7, and the size of the agglomerated crystals is 0.8 μm.

[0106] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was measured by inductively coupled plasma atomic emission spectrometry (ICP) to be 76.

[0107] The N2 physical adsorption graph of the molecular sieve sample is shown in FIG. 2.​Figure 2 As shown in Table 1, by using the hydrogen type ZSM-5 molecular sieve as catalyst, the catalytic cracking reaction of triisopropylbenzene was carried out, and the conditions and reaction results of the catalytic cracking reaction are shown in Table 1. Figure 2 The specific surface area of the molecular sieve sample can be calculated to be 628 meters 2 / gram, the external specific surface area measured by BET method is 158 meters 2 / gram; the total pore volume is 0.39 centimeters 3 / gram, and the micropore volume is 0.20 centimeters 3 / gram.

[0108] The ZSM-5 molecular sieve was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, and then centrifugal washing was carried out. After repeating the ammonium ion exchange and centrifugal washing twice, the sample obtained was dried overnight at 100°C, and then hydrogen type ZSM-5 molecular sieve was prepared by calcining in air at 550°C for 4 hours.

[0109] The hydrogen type ZSM-5 molecular sieve was used as catalyst to carry out the catalytic cracking reaction of triisopropylbenzene, and the conditions and reaction results of the catalytic cracking reaction are shown in Table 1.

[0110] Example 2

[0111] A mixture was prepared by stirring 13.50 grams of deionized water, 0.32 grams of [Pr4-6-6-(OH)2] 3.9 (SDA), 0.008 grams of sodium metaaluminate, and 1.04 grams of tetraethyl orthosilicate at room temperature for 24 hours, and the molar ratio of the final mixture was as follows:

[0112] SiO2 / Al2O3 = 102;

[0113] NaOH / SiO2 = 0.02;

[0114] SDA / SiO2 = 0.16;

[0115] H2O / SiO2 = 150;

[0116] The mixture was loaded into a stainless steel autoclave, and crystallization was carried out under static crystallization conditions at 165°C for 12 days. After crystallization, the molecular sieve sample was obtained by filtering, water washing, drying overnight in an oven at 100°C, and calcining in air at 550°C for 6 hours.

[0117] Figure 3 The X-ray diffraction pattern of the molecular sieve sample is shown in Figure 1, and it can be obtained that the molecular sieve sample is ZSM-5 molecular sieve. Figure 3

[0118] ​It can be obtained from the SEM image of the molecular sieve sample that the molecular sieve sample has a morphology of agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals, and the number ratio of the morphology of agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation symbiosis and 30°±5° rotation symbiosis between adjacent sheet-shaped nanocrystals in the molecular sieve sample is 88%; the thickness of the sheet-shaped nanocrystals is 14 nm, the length is 78 nm, the width is 40 nm, the length-thickness ratio is 5.6, the length-width ratio is 2.0, and the size of the agglomerate crystal is 1.3 μm.

[0119] The SiO2 / Al2O3 molar ratio of the molecular sieve sample is 72, which is measured by inductively coupled plasma atomic emission spectrometry (ICP).

[0120] The N2 physical adsorption graph of the molecular sieve sample is shown in FIG. 2. Figure 2 Similarly, the specific surface area of the molecular sieve is 596 meters 2 / gram, the external specific surface area measured by the BET method is 102 meters 2 / gram; the total pore volume is 0.39 centimeters 3 / gram, and the micropore volume is 0.20 centimeters 3 / gram.

[0121] The ZSM-5 molecular sieve is subjected to ammonium ion exchange with a 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, and then centrifugal washing, and the sample obtained after repeating the ammonium ion exchange and centrifugal washing twice is dried at 100°C overnight, and then calcined in air at 550°C for 4 hours to obtain a hydrogen type ZSM-5 molecular sieve sample.

[0122] The hydrogen type ZSM-5 molecular sieve is used as a catalyst to perform a triisopropylbenzene catalytic cracking reaction, wherein the conditions and reaction results of the catalytic cracking reaction are shown in Table 1.

[0123] Example 3

[0124] A mixture is prepared by stirring 13.50 grams of deionized water, 0.42 grams of [Pr4-6-6-(OH)2] 3.9 (SDA), 0.008 grams of aluminum hydroxide, and 1.04 grams of tetraethyl orthosilicate at room temperature for 24 hours, and the molar ratio of the final mixture is:

[0125] SiO2 / Al2O3=97;

[0126] SDA / SiO2=0.21;

[0127] H2O / SiO2=150.

[0128] The mixture was loaded into a stainless steel autoclave, and crystallization was carried out at 165 °C under static crystallization conditions for 14 days. After crystallization, the mixture was filtered, washed with water, and dried in an oven at 100 °C overnight. The molecular sieve sample was obtained after calcination of the dried mixture in air at 550 °C for 6 hours.

[0129] Figure 4 The X-ray diffraction pattern of the molecular sieve sample is shown in FIG. 1. Figure 4 The molecular sieve sample was determined to be ZSM-5 molecular sieve.

[0130] Figure 5 The SEM image of the molecular sieve sample is shown in FIG. 2. The SEM image of the molecular sieve sample shows that the molecular sieve sample has a morphology of agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals, and the proportion of the agglomerate crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve sample is 92%. The thickness of the sheet-shaped nanocrystals is 80 nm, the length is 640 nm, the width is 330 nm, the length-thickness ratio is 8.0, the length-width ratio is 1.9, and the size of the agglomerate crystals is 0.8 μm.

[0131] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was determined to be 92 by inductively coupled plasma atomic emission spectrometry (ICP).

[0132] The N2 physical adsorption graph of the molecular sieve sample is shown in FIG. 3. Figure 2 Similarly, the specific surface area of the molecular sieve sample was determined to be 614 m 2 / g, the external specific surface area was determined to be 124 m 2 / g by the BET method; the total pore volume was 0.38 cm 3 / g, and the micropore volume was 0.19 cm 3 / g.

[0133] The molecular sieve sample was used as a catalyst for a triisopropylbenzene catalytic cracking reaction. The conditions and results of the catalytic cracking reaction are shown in Table 1.

[0134] Example 4

[0135] A mixture was prepared by stirring 26.10 g of deionized water, 0.84 g of [Pr4-6-6-(OH)2] 3.9 (SDA), 0.19 g of sodium hydroxide aqueous solution (30% mass concentration), 0.008 g of sodium metaaluminate, and 2.08 g of tetraethyl orthosilicate at room temperature for 24 hours. The molar ratio of the final mixture was as follows:

[0136] SiO2 / Al2O3 = 204;

[0137] NaOH / SiO2 = 0.15;

[0138] SDA / SiO2= 0.21;

[0139] H2O / SiO2= 146;

[0140] The mixture was loaded into a stainless steel autoclave, and crystallization was carried out at 160 °C under static crystallization conditions for 7 days. After crystallization, the mixture was filtered, washed with water, and dried in an oven at 100 °C overnight. The molecular sieve sample obtained after calcination in air at 550 °C for 6 hours was obtained.

[0141] Figure 6 The X-ray diffraction pattern of the molecular sieve sample is shown in FIG. 1. Figure 6 It can be seen from the X-ray diffraction pattern that the molecular sieve sample is a ZSM-5 molecular sieve.

[0142] It can be seen from the SEM image of the molecular sieve sample that the molecular sieve sample has a morphology of agglomerated crystals formed by cross-assembly of sheet-shaped nanocrystals, and the proportion of the morphology of agglomerated crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve sample is 86%. The thickness of the sheet-shaped nanocrystals is 16 nm, the length is 230 nm, the width is 120 nm, the length-thickness ratio is 14.4, the length-width ratio is 1.9, and the size of the agglomerated crystals is 0.9 μm.

[0143] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was measured by inductively coupled plasma atomic emission spectrometry (ICP) to be 183.

[0144] The N2 physical adsorption graph of the molecular sieve sample is shown in FIG. 2. Figure 2 Similarly, the specific surface area of the molecular sieve sample is 596 meters 2 / gram, the external specific surface area measured by the BET method is 112 meters 3 / gram; the total pore volume is 0.42 centimeters 3 / gram, and the micropore volume is 0.20 centimeters 3.9 / gram.

[0145] The ZSM-5 molecular sieve was subjected to ammonium ion exchange with a 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65 °C for 3 hours, followed by centrifugal washing. The sample obtained after repeating the ammonium ion exchange and centrifugal washing twice was dried overnight at 100 °C, and then calcined in air at 550 °C for 4 hours to obtain a hydrogen-type ZSM-5 molecular sieve.

[0146] The hydrogen-type ZSM-5 molecular sieve was used as a catalyst for triisopropylbenzene catalytic cracking reaction. The conditions and results of the catalytic cracking reaction are shown in Table 1.

[0147] Example 5

[0148] A mixture was prepared by stirring 13.50 g of deionized water, 0.42 g of [Pr4-6-6-(OH)2] 3.9 (SDA), 1.04 g of tetraethyl orthosilicate, and the molar ratio of the final mixture was:

[0149] SDA / SiO2= 0.21;

[0150] H2O / SiO2= 150;

[0151] The mixture was loaded into a stainless steel autoclave and heated under static crystallization conditions at 160°C for 8 days. After crystallization, the product was filtered, washed with water, and dried in an oven at 100°C overnight. The molecular sieve sample was obtained after calcination in air at 550°C for 6 hours.

[0152] Figure 7 The X-ray diffraction pattern of the molecular sieve sample was obtained by Figure 7 The molecular sieve sample was a pure-silicon ZSM-5 (Silicalite-1) molecular sieve.

[0153] Figure 8 The SEM image of the molecular sieve sample was obtained by The SEM image of the molecular sieve sample showed that the molecular sieve sample had a morphology of agglomerate crystals formed by the cross-assembly of sheet-shaped nanocrystals, and the proportion of the morphology of agglomerate crystals formed by the cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation and 30°±5° rotation between adjacent sheet-shaped nanocrystals in the molecular sieve sample was 89%. The thickness was 130 nm, the length was 1800 nm, the width was 1100 nm, the length-thickness ratio was 13.8, the length-width ratio was 1.6, and the size of the agglomerate crystal was 2.1 μm.

[0154] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was greater than 2000, as measured by inductively coupled plasma atomic emission spectrometry (ICP), and the molecular sieve sample was a pure-silicon ZSM-5 molecular sieve.

[0155] The N2 physical adsorption graph of the molecular sieve sample was similar to Figure 2 The specific surface area of the molecular sieve sample was 584 meters 2 / gram, the external specific surface area measured by the BET method was 106 meters 2 / gram; the total pore volume was 0.42 centimeters 3 / gram, and the micropore volume was 0.19 centimeters 3 / gram.

[0156] The molecular sieve sample was used as a catalyst for the Beckmann rearrangement reaction of cyclohexanone oxime, and the reaction conditions were as follows: 5wt% cyclohexanone oxime-ethanol solution, reaction temperature 370°C, and space velocity 3.5h -1The conversion of cyclohexanone oxime is 93%, and the selectivity of caprolactam is 95%.

[0157] Example 6

[0158] A mixture was prepared by stirring 13.05 g of deionized water, 0.42 g of [Pr4-6-6-(OH)2] 5.2 (SDA), 0.03 g of sodium metaaluminate, 0.09 g of sodium hydroxide aqueous solution (30% mass concentration), 1.04 g of tetraethyl orthosilicate at room temperature for 24 hours, and the molar ratio of the final mixture was:

[0159] SiO2 / Al2O3 = 27;

[0160] NaOH / SiO2 = 0.20;

[0161] SDA / SiO2 = 0.21;

[0162] H2O / SiO2 = 145.

[0163] The mixture was loaded into a stainless steel autoclave, and the crystallization was carried out at 170°C under static crystallization conditions for 5 days. After the crystallization was completed, the mixture was filtered, washed with water, and dried in an oven at 100°C overnight. The molecular sieve sample was obtained after calcination of the dried sample in air at 550°C for 6 hours.

[0164] The X-ray diffraction pattern of the molecular sieve sample was similar to that of Figure 1 ZSM-5 molecular sieve.

[0165] It can be seen from the SEM image of the molecular sieve sample that the molecular sieve sample has a morphology of agglomerated crystals formed by cross-assembly of sheet-shaped nanocrystals, and the proportion of the morphology of agglomerated crystals formed by cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation intergrowth and 30°±5° rotation intergrowth between adjacent sheet-shaped nanocrystals in the molecular sieve sample is 83%. The thickness of the sheet-shaped nanocrystals is 75 nm, the length is 620 nm, the width is 370 nm, the length-thickness ratio is 8.3, the length-width ratio is 1.7, and the size of the agglomerated crystals is 1.9 μm.

[0166] The SiO2 / Al2O3 molar ratio of the molecular sieve sample was measured by inductively coupled plasma atomic emission spectrometry (ICP) to be 25.

[0167] The N2 physical adsorption graph of the molecular sieve sample was similar to that of Figure 2 ZSM-5 molecular sieve. 2 The specific surface area of the molecular sieve sample was 586 m 2 / g, the external specific surface area measured by the BET method was 137 m 3 / g; the total pore volume was 0.43 cm 3 / g, and the micropore volume was 0.20 cm / g.

[0168] The ZSM-5 molecular sieve was subjected to ammonium ion exchange with 0.2 mol / L of NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, and then centrifuged and washed. The sample obtained after repeating the ammonium ion exchange and centrifugal washing twice was dried overnight at 100°C and calcined in air at 550°C for 4 hours to obtain a hydrogen-type ZSM-5 molecular sieve.

[0169] The hydrogen-type ZSM-5 molecular sieve was used as a catalyst for the catalytic cracking reaction of triisopropylbenzene. The conditions and results of the catalytic cracking reaction are shown in Table 1.

[0170] Example 7

[0171] The mixture was prepared according to the method of Example 1, except that [Pr4-6-6-Br2] 9.7 was used instead of [Pr4-6-6-(OH)2] 3.9 , and the amounts of the raw materials were controlled so that the molar ratio of the final mixture was:

[0172] SiO2 / Al2O3 = 50;

[0173] NaOH / SiO2 = 0.15;

[0174] SDA / SiO2 = 0.21;

[0175] H2O / SiO2 = 25;

[0176] The mixture was loaded into a stainless steel autoclave and heated for crystallization under static crystallization conditions at 175°C for 4 days. After the crystallization was completed, the sample was filtered, washed with water, dried overnight in an oven at 100°C, and calcined in air at 550°C for 6 hours to obtain a molecular sieve sample.

[0177] The X-ray diffraction pattern of the molecular sieve sample was similar to Figure 1 , and the molecular sieve sample was determined to be a ZSM-5 molecular sieve.

[0178] The SEM image of the molecular sieve sample was similar to Figure 2 , and the molecular sieve sample was determined to have a morphology of agglomerated crystals formed by the cross-assembly of sheet-shaped nanocrystals. The proportion of the number of agglomerated crystals formed by the cross-assembly of sheet-shaped nanocrystals with 90°±10° rotation twinning and 30°±5° rotation twinning between adjacent sheet-shaped nanocrystals in the molecular sieve sample was 86%. The thickness, length, and width of the sheet-shaped nanocrystals were 15 nm, 60 nm, and 40 nm, respectively, the length-thickness ratio was 4.0, the length-width ratio was 1.5, and the size of the agglomerated crystals was 1.2 μm.

[0179] The SiO2 / Al2O3 molar ratio of the molecular sieve was 45, which was measured by inductively coupled plasma atomic emission spectrometry (ICP).

[0180] The N2 physical adsorption graph of the molecular sieve sample was similar to Figure 2 Similarly, the specific surface area of the molecular sieve sample was 620 meters 2 / gram, the external specific surface area measured by the BET method was 146 meters 2 / gram; the total pore volume was 0.37 centimeters 3 / gram, and the micropore volume was 0.19 centimeters 3 / gram.

[0181] The ZSM-5 molecular sieve was subjected to ammonium ion exchange with a 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, and then centrifuged and washed. After repeating the ammonium ion exchange and centrifugal washing twice, the sample was dried overnight at 100°C and calcined in air at 550°C for 4 hours to obtain a hydrogen type ZSM-5 molecular sieve.

[0182] The hydrogen type ZSM-5 molecular sieve was used as a catalyst for the catalytic cracking reaction of triisopropylbenzene. The conditions and results of the catalytic cracking reaction are shown in Table 1.

[0183] Example 8

[0184] The mixture was prepared according to the method of Example 1, except that the tetraethyl orthosilicate was replaced with silica sol (40% mass concentration), and the addition amounts of the raw materials were controlled so that the final mixture had the same molar ratio as in Example 1.

[0185] The X-ray diffraction graph of the molecular sieve sample was similar to Figure 1 Similarly, it was found that the molecular sieve sample was a ZSM-5 molecular sieve.

[0186] The SEM graph of the molecular sieve sample was similar to Figure 2 Similarly, it was found that the molecular sieve sample had a morphology of agglomerated crystals formed by the cross assembly of sheet-shaped nanocrystals, and the proportion of the morphology of agglomerated crystals formed by the cross assembly of sheet-shaped nanocrystals with 90°±10° rotation and 30°±5° rotation between adjacent sheet-shaped nanocrystals in the molecular sieve sample was 86%. The thickness of the sheet-shaped nanocrystals was 25 nm, the length was 165 nm, the width was 110 nm, the length-thickness ratio was 6.6, the length-width ratio was 1.5, and the size of the agglomerated crystals was 1.4 μm.

[0187] The SiO2 / Al2O3 molar ratio of the molecular sieve was 88, which was measured by inductively coupled plasma atomic emission spectrometry (ICP).

[0188] The N2 physical adsorption graph of the molecular sieve sample was similar to Figure 2 Similarly, the specific surface area of the molecular sieve sample was 628 meters2 external specific surface area of 151 m2 / g, measured by the BET method 2 total pore volume of 0.40 cm3 / g 3 micropore volume of 0.18 cm3 / g 3 micropore volume of 0.18 cm3 / g.

[0189] The ZSM-5 molecular sieve was subjected to ammonium ion exchange with a 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, and then centrifugally washed. The sample obtained after repeating the ammonium ion exchange and centrifugal washing twice was dried overnight at 100°C and calcined in air at 550°C for 4 hours to obtain a hydrogen-type ZSM-5 molecular sieve.

[0190] The hydrogen-type ZSM-5 molecular sieve was used as a catalyst to perform a triisopropylbenzene catalytic cracking reaction. The conditions and reaction results of the catalytic cracking reaction are shown in Table 1.

[0191] Comparative Example 1

[0192] The mixture was prepared according to the method of Example 5, except that an aqueous solution of tetrapropylammonium hydroxide (25% mass concentration) (SDA) was used to replace [Pr4-6-6-(OH)2] 3.9 , and the addition amounts of the raw materials were controlled so that the molar ratio of the final mixture was the same as that of Example 5.

[0193] The X-ray diffraction pattern of the molecular sieve sample was similar to Figure 1 , and a pure-silicon ZSM-5 (Silicalite-1) molecular sieve was obtained.

[0194] The SEM image of the molecular sieve sample is shown in Figure 9 The molecular sieve sample had a chess piece-like morphology, and did not have the morphology of agglomerate crystals formed by cross-assembly of 90°±10° rotation intergrowths and 30°±5° rotation intergrowth sheet-like nanocrystals.

[0195] The molecular sieve sample was used as a catalyst to perform a Beckmann rearrangement reaction of cyclohexanone oxime. The reaction conditions were as follows: 5 wt% cyclohexanone oxime-ethanol solution, reaction temperature 370°C, and space velocity 3.5 h -1 The conversion rate of cyclohexanone oxime was 79%, and the selectivity of caprolactam was 84%.

[0196] Comparative Example 2

[0197] The mixture was prepared according to the method of Example 1, except that an aqueous solution of tetrapropylammonium hydroxide (25% mass concentration) (SDA) was used to replace [Pr4-6-6-(OH)2] 3.9 , and the addition amounts of the raw materials were controlled so that the molar ratio of the final mixture was the same as that of Example 7.

[0198] The X-ray diffraction pattern of the molecular sieve sample is similar to that of ZSM-5 molecular sieve. Figure 1 Similarly, the molecular sieve sample is ZSM-5 molecular sieve.

[0199] The SEM image of the molecular sieve sample is shown in Figure 2. Figure 10 As shown in Figure 2, the molecular sieve sample has a morphology of large crystal grains, and does not have the morphology of agglomerate crystal formed by cross assembly of 90°±10° rotation intergrowth and 30°±5° rotation intergrowth sheet-like nanocrystals.

[0200] The ZSM-5 molecular sieve was subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, and then centrifuged and washed. The sample obtained after repeating the ammonium ion exchange and centrifugation and washing twice was dried overnight at 100°C, and then calcined in air at 550°C for 4 hours to obtain hydrogen-type ZSM-5 molecular sieve.

[0201] The hydrogen-type ZSM-5 molecular sieve was used as a catalyst for triisopropylbenzene catalytic cracking reaction. The conditions and reaction results of the catalytic cracking reaction are shown in Table 1.

[0202] Table 1

[0203]

[0204] As can be seen from the results in the examples and comparative examples, the ZSM-5 molecular sieve in the present application has obviously better effect when used as a catalyst for triisopropylbenzene catalytic cracking and Beckmann rearrangement of cyclohexanone oxime to caprolactam.

[0205] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed in the present application, and all fall within the protection scope of the present application.

Claims

1. A ZSM-5 molecular sieve, characterized in that, The ZSM-5 molecular sieve has an aggregate crystal morphology formed by the cross-assembly of plate-like nanocrystals, and the adjacent plate-like nanocrystals in the molecular sieve have an aggregate crystal morphology formed by the cross-assembly of plate-like nanocrystals with 90°±10° rotational symbiosis and 30°±5° rotational symbiosis. The proportion of the number of the aggregate crystal morphologies formed by the cross-assembly of plate-like nanocrystals with 90°±10° rotational symbiosis and 30°±5° rotational symbiosis among the adjacent plate-like nanocrystals in the molecular sieve is greater than or equal to 80%.

2. The ZSM-5 molecular sieve according to claim 1, wherein, The proportion of aggregate crystal morphologies formed by the cross-assembly of adjacent sheet-like nanocrystals in the molecular sieve, consisting of 90°±10° rotational symbiosis and 30°±5° rotational symbiosis, is 80-100%; and / or The aggregate crystals are 0.5-3.0 μm in size; and / or The aspect ratio of the sheet-like nanocrystals is 1.2-2.5; and / or The aspect ratio of the sheet-like nanocrystals is 4-20.

3. The ZSM-5 molecular sieve according to claim 2, wherein, The aggregate crystals are 0.6-2.5 μm in size; and / or The aspect ratio of the sheet-like nanocrystals is 1.2-2.0; and / or The aspect ratio of the sheet-like nanocrystals is 4-15.

4. The ZSM-5 molecular sieve according to claim 2, wherein, The length of the sheet-like nanocrystals is 30-2500 nm; and / or The width of the sheet-like nanocrystals is 20-1500 nm; and / or The thickness of the sheet-like nanocrystals is 5-150 nm.

5. The ZSM-5 molecular sieve according to claim 4, wherein, The length of the sheet-like nanocrystals is 30-2200 nm; and / or The width of the sheet-like nanocrystals is 20-1300 nm; and / or The thickness of the sheet-like nanocrystals is 8-130 nm.

6. The ZSM-5 molecular sieve according to claim 1, wherein, The SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is greater than or equal to 20; and / or The total specific surface area of ​​the ZSM-5 molecular sieve is not less than 450 m². 2 / gram; and / or The specific surface area of ​​the ZSM-5 molecular sieve is not less than 60 m². 2 / gram.

7. The ZSM-5 molecular sieve according to claim 6, wherein, The total specific surface area of ​​the ZSM-5 molecular sieve is 450-700 m². 2 / gram; and / or The ZSM-5 molecular sieve has an external specific surface area of ​​60-200 m². 2 / gram.

8. The ZSM-5 molecular sieve according to claim 1, wherein, The total pore volume of the ZSM-5 molecular sieve is not less than 0.35 cm³. 3 / gram; and / or The micropore volume of the ZSM-5 molecular sieve is not less than 0.12 cm³. 3 / gram.

9. The ZSM-5 molecular sieve according to claim 8, wherein, The total pore volume of the ZSM-5 molecular sieve is 0.35-0.60 cm³. 3 / gram; and / or The ZSM-5 molecular sieve has a micropore volume of 0.12-0.24 cm³. 3 / gram.

10. A method for preparing the ZSM-5 molecular sieve according to any one of claims 1-9, characterized in that, The preparation method includes: crystallizing a silicon-containing raw material mixture in the presence of a structure-directing agent. The structure-directing agent contains the structural unit a shown in formula (1). Equation (1), In equation (1), X is a halide ion or hydroxide ion, and * indicates a connection site.

11. The preparation method according to claim 10, wherein, The structure-directing agent has an average degree of polymerization of 2-20; and / or The silicon source is measured in molar amounts of SiO2, and the structure directing agent is measured in molar amounts of structural unit a, wherein the molar ratio of the silicon source to the structure directing agent is 1:(0.1-0.3); and / or The silicon source is provided in molar amounts of SiO2, and the molar ratio of the silicon source to the solvent in the raw material mixture is 1:(15-180); and / or; The silicon source is selected from at least one of tetraethyl orthosilicate, fumed silica, silica sol, and silica fume.

12. The preparation method according to claim 11, wherein, The structure-directing agent has an average degree of polymerization of 3-12.

13. The preparation method according to claim 10, wherein, The raw material mixture also contains an optional aluminum source and / or alkali source.

14. The preparation method according to claim 13, wherein, When the raw material mixture contains an aluminum source, the molar ratio of the silicon source to the aluminum source, based on the molar amount of SiO2 provided and the aluminum source, based on the molar amount of Al2O3 provided, is 1:(0-0.05), and not 0; and / or When the raw material mixture contains an alkali source, the molar ratio of the silicon source to the alkali source, measured by the molar amount of SiO2 provided and the alkali source, measured by the molar amount of cations provided, is 1:(0-0.3), and not 0; and / or When the raw material mixture contains an aluminum source, the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum hydroxide, sodium aluminate, boehmite, and aluminum isopropoxide; and / or When the raw material mixture contains an alkaline source, the alkaline source is selected from at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

15. The preparation method according to claim 10, wherein, The conditions for the crystallization treatment include: The crystallization temperature is 120-190℃; and / or Crystallization time is 2-15 days.

16. The preparation method according to claim 15, wherein, The conditions for the crystallization treatment include: Crystallization temperature is 140-180℃; and / or Crystallization time is 3-14 days.

17. The preparation method according to claim 10, wherein, The preparation method also includes separation and calcination after crystallization treatment.

18. The preparation method according to claim 17, wherein, The conditions for roasting include: Conducted in an oxygen-containing atmosphere; and / or The roasting temperature is 300-800℃; and / or The roasting time is 1-10 hours.

19. The preparation method according to claim 18, wherein, The conditions for roasting include: The roasting temperature is 400-650℃; and / or The roasting time is 3-6 hours.

20. The use of the ZSM-5 molecular sieve according to any one of claims 1-9 in adsorption treatment and / or organic compound conversion reactions.

21. The application according to claim 20, wherein, The organic compound conversion reactions include olefin isomerization, catalytic cracking of one or more of cumene, dicumene, and tricumene, and the Beckmann rearrangement of cyclohexanone oxime to caprolactam.

22. A method for catalytic cracking of triisopropylbenzene, characterized in that, The method includes: Triisopropylbenzene undergoes a catalytic cracking reaction in the presence of ZSM-5 molecular sieve as described in any one of claims 1-9 and / or hydrogen-form ZSM-5 molecular sieve modified with hydrogen form as described in any one of claims 1-9.

23. The method according to claim 22, wherein, The conditions for the catalytic cracking reaction include: The reaction temperature is 270-350℃; and / or Triisopropylbenzene's weight hourly space velocity (GHSV) is 3-6 h⁻¹ -1 .

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