ZSM-12 molecular sieve and preparation method thereof

Abstract

The invention discloses a ZSM-12 molecular sieve and a preparation method thereof. The morphology of the ZSM-12 molecular sieve is of a laminated cross type. The preparation method of the ZSM-12 molecular sieve comprises the following steps: introducing a molecular sieve gel precursor formed by a silicon source, an aluminum source, an alkali source, a template agent, an additive and water and a copolymer into an aging and crystallization integrated supergravity device, pressurizing, and carrying out supergravity rotation, circulation, re-aging and pressurized crystallization treatment to obtain the ZSM-12 molecular sieve. The molecular sieve provided by the invention has new morphological characteristics, is in a laminated cross type, and can be used in the field of catalytic production.

Description

Technical Field

[0001] This invention relates to the field of zeolite molecular sieve catalysis, and more specifically to a ZSM-12 molecular sieve and its preparation method. Background Technology

[0002] ZSM-12 zeolite molecular sieves were first synthesized in 1974. Due to their pore size, which is close to that of macropores and mesopores, they have a very broad application prospect. ZSM-12 zeolite molecular sieves are monoclinic crystals, possessing a one-dimensional linear non-intersecting pore structure of twelve circular rings, with an aperture size of approximately 0.57 × 0.61 nm. To date, the main method used for synthesizing ZSM-12 molecular sieves is hydrothermal synthesis. Static hydrothermal crystallization suffers from problems such as long crystallization time, low stability, and poor reproducibility.

[0003] CN202210103841.X discloses a method for preparing ZSM-12 molecular sieve, comprising the following steps: (1) mixing an inorganic alkali, a silicon-containing compound, an aluminum-containing compound, a template agent and water, mixing evenly and then performing a hydrothermal crystallization reaction, followed by further separation, washing and drying; (2) mixing the solid material obtained in step (1) with an alkaline solution, and then performing calcination treatment; (3) mixing the solid material obtained in step (2) with a silicon-containing compound, an aluminum-containing compound, an inorganic alkali, a template agent and water, mixing evenly and then performing treatment, followed by separation and drying to obtain ZSM-12 molecular sieve. CN202111252029.5 discloses a small-crystal ZSM-12 molecular sieve and its preparation method. The small-crystal ZSM-12 molecular sieve uses a silica-alumina gel with a relatively high silica-to-alumina ratio (especially acid-treated silica-alumina gel) as a composite silica-alumina source, and is prepared by crystallization using acid-treated silica-alumina gel, inorganic alkali, template agent 1,4-bis(N-methylpyrrolidine)butane halide, and water as raw materials. The synthesized ZSM-12 molecular sieve has high crystallinity, an adjustable silica-to-alumina ratio, regular morphology, and a crystal size of 100-200 nm. CN201710174606.0 discloses a bifunctional template agent for the guided synthesis of hierarchical porous ZSM-12 zeolite molecular sieves, its preparation method, and a molecular sieve based thereon. The template agent requires at least one of 1,4-dichlorobenzyl, α,α'-dibromo-p-xylene, and 1,4-benzenediol to be dissolved in a solvent with at least one of N,N,N',N'-tetramethyl-1,3-butanediamine, N,N,N',N'-tetramethyl-1,5-pentanediamine, N,N-dimethylhexylamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, and their homologues, followed by heating and holding the reaction at a specific temperature to obtain the bifunctional template agent. Using this template agent, a one-step hydrothermal method can be used to obtain ZSM-12 molecular sieves with mesoporous-microporous hierarchical pores. Summary of the Invention

[0004] This invention provides a novel ZSM-12 molecular sieve and its preparation method. This molecular sieve exhibits novel morphological characteristics, being a layered, cross-laminated type, and can be used in catalytic production.

[0005] The first aspect of the present invention provides a ZSM-12 molecular sieve, wherein the molecular sieve has a layered cross-shaped morphology.

[0006] Furthermore, the number of layers in the stacked, intersecting morphology is 2-50, preferably 3-40, wherein each layer has an olive-shaped morphology.

[0007] Furthermore, in the stacked cross-shaped morphology, each layer is composed of aggregated nanoparticles, with each layer having a thickness of 500-2000 nm, a diameter of 2-10 μm, and a maximum width of 1-3 μm.

[0008] Furthermore, in the stacked-layer cross-type structure, each layer is composed of nanorods with a length of 100-400 nm and a width of 10-50 nm.

[0009] Furthermore, the atomic molar ratio of silicon to aluminum (Si / Al) in the ZSM-12 molecular sieve is not less than 0.5, and preferably 20 to 1000.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned ZSM-12 molecular sieve, comprising the following steps:

[0011] The molecular sieve gel precursor containing silicon source, aluminum source, alkali source, template agent and additives, and water, along with the copolymer, are passed into an integrated aging and crystallization supergravity device, pressurized and rotated under supergravity, circulated, re-aged and pressurized crystallization treatment, to obtain the ZSM-12 molecular sieve.

[0012] Furthermore, the silicon source is at least one of silica sol, tetraethyl orthosilicate, amorphous silica powder, and silicate; the aluminum source is at least one of aluminum sulfate octadecylhydrate, aluminum isopropoxide, aluminate, and aluminate.

[0013] Further, the template agent is at least one selected from n-propylamine, n-butylamine, n-hexylamine, methylamine, ethylamine, ethylenediamine, tetraethylamine hydroxide, tetramethylamine hydroxide, and tetrapropylamine hydroxide.

[0014] Furthermore, the additive is at least one selected from nitroaniline, azobisisobutyronitrile, pyridine, and triethylamine.

[0015] Furthermore, the copolymer is at least one of block polymers, preferably at least one of triblock polyether and polystyrene-b-polymethyl methacrylate (PS-b-PMMA).

[0016] Further, in the triblock polyether with the general formula HO-(EO)x-(PO)y-(EO)zH, the value of x ranges from 15 to 25, the value of y ranges from 65 to 75, and the value of z ranges from 15 to 25, more preferably P123(PEO-20-PPO-70-PEO-20); in the polystyrene-b-polymethyl methacrylate (PS-b-PMMA), the mass fraction of styrene is 0.1-0.7%, the number-average molecular weight of Mn is 100,000-115,000, and the weight-average molecular weight of Mw / number-average molecular weight of Mn is 1-1.27.

[0017] Furthermore, the molecular sieve gel precursor preparation process is as follows: solution A is prepared by mixing silicon source, alkali source, template agent and water; solution B is prepared by mixing aluminum source, additive and water; and solution A and solution B are mixed to obtain the molecular sieve gel precursor.

[0018] Furthermore, in solution A, the molar ratio of silicon source, alkali source, template agent, and water is SiO2:Na2O:template agent:H2O = 1:0.001-1:0.1-0.6:5-1000; in solution B, the molar ratio of aluminum source, additive, and water is Si / Al = 0.5-∞, additive:Al = 0.01-50, and H2O:Al = 5-500.

[0019] Furthermore, the molar ratio of the copolymer to the silicon source, calculated as SiO2, is 0.1-10.

[0020] Furthermore, the molecular sieve gel precursor and copolymer are introduced into an integrated aging and crystallization supergravity device, and the mixture is circulated at least 3 times, preferably 3-8 times.

[0021] Furthermore, the cycle time is 10-240 min, preferably 20-60 min.

[0022] Furthermore, the supergravity rotation speed during the cycle is 500-5000 rpm, preferably 1000-3000 rpm.

[0023] Furthermore, after the molecular sieve gel precursor and copolymer are introduced into the integrated aging and crystallization hypergravity device, pressure needs to be applied during the circulation process. The applied pressure ranges from 0.01 to 20 MPa, preferably from 0.05 to 8 MPa.

[0024] Furthermore, the molecular sieve gel precursor and copolymer are introduced into the integrated aging and crystallization supergravity device in any order. They can be mixed first and then introduced into the device, or they can be introduced into the device simultaneously and mixed. Alternatively, one of the molecular sieve gel precursor or copolymer can be introduced into the device first and then the other material can be introduced and mixed.

[0025] Furthermore, the aging time is 24-96 hours. The aging is carried out under pressure and hypergravity in an integrated aging and crystallization hypergravity device.

[0026] Further, the crystallization conditions are a crystallization temperature of 100-200℃ and a crystallization time of 1-96 hours. Pressurization involves further increasing the pressure under hypergravity conditions within the integrated aging and crystallization hypergravity device. The increased pressure ranges from 0.01-10 MPa, preferably 0.1-8 MPa. The pressurization in this pressurized crystallization process is an increase in pressure based on the previous pressurization.

[0027] Furthermore, after crystallization, molecular sieves can be obtained by conventional washing and drying.

[0028] The molecular sieve provided in the first aspect of the present invention or the molecular sieve prepared by the method described in the second aspect can be applied in the field of catalysis and used as a catalyst and catalyst support.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The ZSM-12 molecular sieve provided by this invention has novel morphological characteristics and can be used in the field of catalytic production. The method provided by this invention can significantly enhance grain shaping and forming effects, achieve mixed-enhanced growth at the microscale, and obtain a novel molecular sieve with a special morphology.

[0031] The preparation method provided by this invention can significantly enhance the mixing effect and is a new method for achieving mixing enhancement at the microscale to obtain molecular sieves with special morphologies. Attached Figure Description

[0032] Figure 1 These are SEM images of the molecular sieves obtained in Example 1;

[0033] Figure 2 The image shows a molecular sieve SEM image obtained in Comparative Example 1.

[0034] Figure 3 The image shows the XRD pattern of the molecular sieve obtained in Example 1. Detailed Implementation

[0035] The technical solution of the present invention will be further illustrated below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0036] In this invention, the scanning electron microscope (SEM) images of the samples were taken on a Hitachi S-4800II scanning electron microscope.

[0037] In this invention, the XRD testing conditions were as follows: molecular sieve phase analysis was performed using a Rigaku-Ultima X-ray diffractometer (Japan). CuKα radiation was used, with a wavelength λ = 0.15432 nm. The X-ray diffraction pattern scanning range 2θ was 5-50°, and the scanning speed was 10° / min.

[0038]

Example 1

[0039] Solution A is prepared by mixing silica sol (silicon source), NaOH (alkali source), n-propylamine (templating agent), and water according to the material molar ratio of SiO2:Na2O:n-propylamine:H2O = 1:0.4:0.2:50. Solution B is prepared by mixing aluminum isopropoxide (aluminum source), pyridine (additive), and water according to the material molar ratio of Si / Al = 60, pyridine:Al = 0.6, and H2O:Al = 50. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The resulting molecular sieve gel precursor, with a molar ratio of 0.2P123:SiO2, was mixed with copolymer P123 and passed through an integrated aging and crystallization hypergravity apparatus. The apparatus was circulated three times at a hypergravity speed of 2000 rpm, each cycle lasting 20 minutes, with a pressure of 0.3 MPa. After standing for 72 hours, the pressure was increased to 0.3 MPa, and crystallization was carried out at 150°C for 24 hours. After crystallization, the product was washed and dried to obtain a "layered cross-linked" ZSM-12 molecular sieve. (See...) Figure 1 .pass Figure 1 It can be seen that the morphology is a stacked, cross-laminated structure with 5-20 layers. Each layer has an olive-shaped morphology, with a thickness of 600-1000 nm, a diameter of 3-8 μm, and a maximum width of 1-2 μm. Each layer in the stacked, cross-laminated structure consists of nanorods with a length of 200-300 nm and a width of 20-30 nm.

[0040] The XRD diffraction pattern of the molecular sieve is shown below. Figure 3 ,Depend on Figure 3 It can be identified as ZSM-12 molecular sieve.

[0041]

Example 2

[0042] Solution A is prepared by mixing silica sol (silicon source), NaOH (alkali source), ethylenediamine (templative agent), and water in a molar ratio of SiO2:Na2O:ethylenediamine:H2O of 1:0.2:0.3:70. Solution B is prepared by mixing aluminum sulfate octahydrate (aluminum source), triethylamine (additive), and water in a molar ratio of Si / Al = 80, triethylamine:Al = 0.7, and H2O:Al = 100. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor and copolymer PS-b-PMMA were introduced into an integrated aging and crystallization hypergravity device with a molar ratio of 0.4 PS-b-PMMA:SiO2, Mn = 100000, Mw weight average molecular weight / Mn number average molecular weight = 1.08, hypergravity rotation speed 1500 rpm, 4 cycles, each cycle time 30 min, with a pressure of 0.7 MPa. After standing for 72 hours, the pressure was increased to 0.4 MPa, and crystallization was carried out at 160℃ for 36 h. After crystallization, the "layered cross-type" ZSM-12 molecular sieve was obtained by washing and drying.

[0043] SEM image and Figure 1 Similarly, it exhibits a layered, cross-hatched morphology with 3-5 layers. Each layer has an olive-shaped morphology, with a thickness of 800-1200 nm, a diameter of 4-8 μm, and a maximum width of 2-3 μm. Each layer in the layered, cross-hatched morphology consists of nanorods with a length of 100-300 nm and a width of 20-40 nm.

[0044] The XRD pattern is similar to that of Example 1, showing ZSM-12 molecular sieve.

[0045]

Example 3

[0046] Solution A is prepared by mixing tetraethyl orthosilicate (silicon source), NaOH (alkali source), n-hexylamine (templating agent), and water according to the material molar ratio of SiO2:Na2O:n-hexylamine:H2O = 1:0.4:0.6:100. Solution B is prepared by mixing aluminum sulfate octadecylhydrate (aluminum source), azobisisobutyronitrile (additive), and water according to the material molar ratio of Si / Al = 50, azobisisobutyronitrile:Al = 0.5, and H2O:Al = 200. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor and copolymer P123 were introduced into an integrated aging and crystallization hypergravity device with a copolymer molar ratio of 0.3P123:SiO2, a hypergravity rotation speed of 1500rpm, and 4 cycles, each cycle lasting 25min. The pressure added was 0.8MPa. After standing for 72 hours, the pressure was increased to 0.3MPa and crystallized at 150℃ for 48 hours. After crystallization, the product was washed and dried to obtain a "layered cross-type" ZSM-12 molecular sieve.

[0047] SEM image and Figure 1 Similarly, it exhibits a layered, cross-hatched morphology with 3-8 layers. Each layer has an olive-shaped morphology, with a thickness of 1000-1500 nm, a diameter of 3-8 μm, and a maximum width of 1-3 μm. Each layer in the layered, cross-hatched morphology consists of nanorods with a length of 200-300 nm and a width of 30-40 nm.

[0048] The XRD pattern is similar to that of Example 1, showing ZSM-12 molecular sieve.

[0049]

Example 4

[0050] Solution A is prepared by mixing silica sol (silicon source), NaOH (alkali source), n-propylamine (templative agent), and water in a molar ratio of SiO2:Na2O:n-propylamine:H2O of 1:0.3:0.5:50. Solution B is prepared by mixing aluminum isopropoxide (aluminum source), triethylamine (additive), and water in a molar ratio of Si / Al = 70, triethylamine:Al = 0.7, and H2O:Al = 50. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The resulting molecular sieve gel precursor, with a molar ratio of 0.2P123:SiO2, was mixed with copolymer P123 and passed through an integrated aging and crystallization hypergravity apparatus. The apparatus was circulated three times at 2000 rpm for 20 minutes each time, with a pressure of 0.2 MPa. After standing for 72 hours, the pressure was increased to 0.3 MPa, and crystallization was carried out at 150°C for 32 hours. After crystallization, the product was washed and dried to obtain a "layered cross-linked" ZSM-12 molecular sieve. SEM images are shown below. Figure 1 Similarly, it exhibits a layered, cross-hatched morphology with 5-20 layers. Each layer has an olive-shaped morphology, with a thickness of 700-900 nm, a diameter of 3-8 μm, and a maximum width of 1-2 μm. Each layer in the layered, cross-hatched morphology consists of nanorods with a length of 200-300 nm and a width of 20-40 nm.

[0051] The XRD pattern is similar to that of Example 1, showing ZSM-12 molecular sieve.

[0052]

Example 5

[0053] Solution A is prepared by mixing silica sol (silicon source), NaOH (alkali source), ethylenediamine (templative agent), and water in a molar ratio of SiO2:Na2O:ethylenediamine:H2O of 1:0.2:0.3:70. Solution B is prepared by mixing aluminum sulfate octahydrate (aluminum source), pyridine (additive), and water in a molar ratio of Si / Al = 80, pyridine:Al = 0.7, and H2O:Al = 100. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor and copolymer PS-b-PMMA were introduced into an integrated aging and crystallization hypergravity device with a molar ratio of 0.4 PS-b-PMMA:SiO2, copolymer PS-b-PMMA, Mn = 100000, Mw weight average molecular weight / Mn number average molecular weight = 1.08, hypergravity rotation speed 1200 rpm, 4 cycles, each cycle time 30 min, with a pressure of 0.5 MPa. After standing for 72 hours, the pressure was increased to 0.3 MPa, and crystallization was carried out at 160℃ for 36 h. After crystallization, the "layered cross-type" ZSM-12 molecular sieve was obtained by washing and drying.

[0054] SEM image and Figure 1 Similarly, it exhibits a layered, cross-hatched morphology with 3-5 layers. Each layer has an olive-shaped morphology, with a thickness of 700-1100 nm, a diameter of 4-8 μm, and a maximum width of 2-3 μm. Each layer in the layered, cross-hatched morphology consists of nanorods with a length of 150-300 nm and a width of 25-40 nm.

[0055] The XRD pattern is similar to that of Example 1, showing ZSM-12 molecular sieve.

[0056]

Example 6

[0057] Solution A is prepared by mixing tetraethyl orthosilicate (silicon source), NaOH (alkali source), n-hexylamine (templating agent), and water in a molar ratio of SiO2:Na2O:n-hexylamine:H2O of 1:0.7:0.6:100. Solution B is prepared by mixing aluminum source aluminum sulfate octahydrate, triethylamine (additive), and water in a molar ratio of Si / Al = 70, triethylamine:Al = 0.6, and H2O:Al = 200. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor and copolymer P123 were introduced into an integrated aging and crystallization hypergravity device with a copolymer molar ratio of 0.3P123:SiO2, a hypergravity rotation speed of 2000rpm, and 3 cycles, each cycle lasting 35min. The pressure added was 0.6MPa. After standing for 72 hours, the pressure was increased to 0.5MPa and crystallized at 150℃ for 48 hours. After crystallization, the product was washed and dried to obtain a "layered cross-type" ZSM-12 molecular sieve.

[0058] SEM image and Figure 1 Similarly, it exhibits a layered, cross-hatched morphology with 3-8 layers. Each layer has an olive-shaped morphology, with a thickness of 1300-1600 nm, a diameter of 4-7 μm, and a maximum width of 1-5 μm. Each layer in the layered, cross-hatched morphology consists of nanorods with a length of 200-300 nm and a width of 30-40 nm.

[0059] The XRD pattern is similar to that of Example 1, showing ZSM-12 molecular sieve.

[0060]

Example 7

[0061] Solution A is prepared by mixing silica sol (silicon source), NaOH (alkali source), ethylenediamine (templative agent), and water according to the molar ratio of SiO2:Na2O:ethylenediamine:H2O = 1:0.3:0.5:50. Solution B is prepared by mixing aluminum sulfate octadecylhydrate (aluminum source), azobisisobutyronitrile (azobisisobutyronitrile) (additive), and water according to the molar ratio of Si / Al = 70, azobisisobutyronitrile:Al = 0.6, and H2O:Al = 110. Solution B is slowly added to solution A and mixed evenly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor and copolymer PS-b-PMMA were introduced into an integrated aging and crystallization hypergravity device with a molar ratio of 0.4 PS-b-PMMA:SiO2, Mn = 100000, Mw weight average molecular weight / Mn number average molecular weight = 1.08, hypergravity rotation speed 2000 rpm, 3 cycles, each cycle time 20 min, with a pressure of 0.3 MPa. After standing for 72 hours, the pressure was increased to 0.2 MPa, and crystallization was carried out at 160℃ for 32 hours. After crystallization, the product was washed and dried to obtain "layered cross-type" ZSM-12 molecular sieve.

[0062] SEM image and Figure 1 Similarly, it exhibits a layered, cross-hatched morphology with 3-5 layers. Each layer has an olive-shaped morphology, with a thickness of 900-1000 nm, a diameter of 5-8 μm, and a maximum width of 2-3 μm. Each layer in the layered, cross-hatched morphology consists of nanorods with a length of 150-200 nm and a width of 30-40 nm.

[0063] The XRD pattern is similar to that of Example 1, showing ZSM-12 molecular sieve.

[0064] Comparative Example 1

[0065] Solution A was prepared by mixing silica sol (silicon source), NaOH (alkali source), n-propylamine (templative agent), and water in a molar ratio of SiO2:Na2O:n-propylamine:H2O of 1:0.4:0.2:50. Solution B was prepared by mixing aluminum isopropoxide (aluminum source), pyridine (additive), and water in a molar ratio of Si / Al = 60, pyridine:Al = 0.6, and H2O:Al = 50. Solution B was slowly added to solution A and mixed thoroughly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor was passed into an integrated aging and crystallization hypergravity device without the addition of copolymer P123. The hypergravity rotation speed was 2000 rpm, and the device was circulated 3 times, with each circulation lasting 20 minutes. No pressure was applied. After standing for 72 hours, the mixture was crystallized at 150℃ for 24 hours. After crystallization, the mixture was washed and dried to obtain spherical molecular sieves. Figure 2 .

[0066] Comparative Example 2

[0067] Solution A was prepared by mixing silica sol (silicon source), NaOH (alkali source), n-propylamine (templative agent), and water in a molar ratio of SiO2:Na2O:n-propylamine:H2O of 1:0.4:0.2:50. Solution B was prepared by mixing aluminum isopropoxide (aluminum source), pyridine (additive), and water in a molar ratio of Si / Al = 60, pyridine:Al = 0.6, and H2O:Al = 50. Solution B was slowly added to solution A and mixed thoroughly to obtain the molecular sieve gel precursor. The formed molecular sieve gel precursor was passed into an integrated aging and crystallization hypergravity device without the addition of copolymer P123. The hypergravity rotation speed was 2000 rpm, and the device was circulated 3 times, with each circulation lasting 20 minutes. The pressure was 0.3 MPa. After standing for 72 hours, the pressure was increased to 0.3 MPa, and the device was crystallized at 150°C for 24 hours. After crystallization, the product was washed and dried to obtain spherical or blocky ZSM-12 molecular sieves.

[0068] Comparative Example 3

[0069] Solution A was prepared by mixing silica sol (silicon source), NaOH (alkali source), n-propylamine (templative agent), and water in a molar ratio of SiO2:Na2O:n-propylamine:H2O of 1:0.4:0.2:50. Solution B was prepared by mixing aluminum isopropoxide (aluminum source), pyridine (additive), and water in a molar ratio of Si / Al = 60, pyridine:Al = 0.6, and H2O:Al = 50. Solution B was slowly added to solution A and mixed thoroughly to obtain the molecular sieve gel precursor. The molecular sieve gel precursor was then passed into an integrated aging and crystallization hypergravity device. Copolymer P123 was added at a ratio of 0.2P123:SiO2. The device was operated at a hypergravity speed of 2000 rpm for 3 cycles, each cycle lasting 20 minutes, without pressure. After standing for 72 hours, crystallization was carried out at 150℃ for 24 hours without pressure. After crystallization, the product was washed and dried to obtain spherical ZSM-12 molecular sieves.

[0070] Comparative Example 4

[0071] Solution A was prepared by mixing silica sol (silicon source), NaOH (alkali source), n-propylamine (templative agent), and water in a molar ratio of SiO2:Na2O:n-propylamine:H2O of 1:0.4:0.2:50. Solution B was prepared by mixing aluminum isopropoxide (aluminum source) and water in a molar ratio of Si / Al = 60 and H2O:Al = 50. Solution B was slowly added to solution A and mixed thoroughly to obtain the molecular sieve gel precursor. The molecular sieve gel precursor was then passed into an integrated aging and crystallization hypergravity device. Copolymer P123 was added at a molar ratio of 0.2P123:SiO2. The device was operated at a hypergravity speed of 2000 rpm for 3 cycles, each cycle lasting 20 minutes, with a pressure of 0.3 MPa. After standing for 72 hours, the device was pressurized to 0.3 MPa and crystallized at 150°C for 24 hours. After crystallization, the product was washed and dried to obtain spherical ZSM-12 molecular sieves.

[0072] The above embodiments describe in detail the preferred embodiments of the present invention; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A ZSM-12 molecular sieve, wherein the morphology of the molecular sieve is a stacked layer cross type.

2. The molecular sieve of claim 1, wherein, The number of layers in the stacked layer cross type morphology is 2-50; and / or preferably, the morphology of each layer is an olive type; and / or preferably, each layer in the stacked layer cross type morphology is aggregated by nanoparticles, wherein the thickness of each layer is 500-2000 nm, the diameter of each layer is 2-10 μm, and the maximum width of each layer is 1-3 μm; and / or preferably, each layer in the stacked layer cross type morphology is composed of nanorods, wherein the length of the nanorods is 100-400 nm, and the width of the nanorods is 10-50 nm.

3. The molecular sieve of claim 1, wherein, The atomic molar ratio of silicon to aluminum (Si / Al) of the ZSM-12 molecular sieve is not less than 0.5, and preferably is 20-1000.

4. A method for preparing the ZSM-12 molecular sieve according to any one of claims 1-3, comprising the following steps: a molecular sieve gel precursor containing a silicon source, an aluminum source, a base source, a template agent, an additive, and water is introduced into an aging and crystallization integrated high gravity device, pressurized and rotated under high gravity, and then subjected to a cycle of recirculation, re-aging, and pressurized crystallization to obtain the ZSM-12 molecular sieve.

5. The method of claim 4, wherein, The silicon source is at least one of silica sol, tetraethyl orthosilicate, amorphous silica powder, and silicate; and / or preferably, the aluminum source is at least one of aluminum sulfate octadecahydrate, aluminum isopropoxide, meta-aluminate, and aluminate; and / or preferably, the template agent is at least one of n-propylamine, n-butylamine, n-hexylamine, methylamine, ethylamine, ethylenediamine, tetraethylammonium hydroxide, tetramethylammonium hydroxide, and tetrapropylammonium hydroxide; and / or preferably, the additive is at least one of nitroaniline, azobisisobutyronitrile, pyridine, and triethylamine; and / or preferably, the copolymer is at least one of a block polymer, preferably a triblock polyether, and polystyrene-b-poly(methyl methacrylate); and / or preferably, the general formula of the triblock polyether is HO-(EO)x-(PO)y-(EO)z-H, wherein x is in the range of 15-25, y is in the range of 65-75, and z is in the range of 15-25, and preferably is P123 (PEO-20-PPO-70-PEO-20); the mass fraction of polystyrene in the polystyrene-b-poly(methyl methacrylate) is 0.1-0.7%, the number average molecular weight (Mn) is 100000-115000, and the weight average molecular weight (Mw) / number average molecular weight (Mn) is 1-1.

27.

6. The method of claim 4, wherein, The preparation process of the molecular sieve gel precursor comprises the following steps: preparing solution A by mixing a silicon source, a base source, a template agent, and water, preparing solution B by mixing an aluminum source, an additive, and water, and mixing solution A and solution B to obtain the molecular sieve gel precursor; and / or preferably, in solution A, the molar ratio of the silicon source, the base source, the template agent, and water, i.e. SiO2:Na2O:template agent:H2O, is 1:0.001-1:0.1-0.6:5-1000; and in solution B, the molar ratio of the aluminum source, the additive, and water, i.e. Si / Al=0.5-∞, additive:Al=0.01-50, H2O:Al=5-500. and / or preferably, the molar ratio of the copolymer to the silicon source, calculated as SiO2, is 0.1-10.

7. The method of claim 4, wherein, The molecular sieve gel precursor and the copolymer are fed into the aging and crystallization integrated supergravity device, the mixture is circulated, and the circulation number is at least 3 times; and / or preferably, the circulation time is 10-240 min each time.

8. The method of claim 4, wherein, The supergravity rotation speed during circulation is 500-5000 rpm, preferably 1000-3000 rpm; and / or preferably, after the molecular sieve gel precursor and the copolymer are fed into the aging and crystallization integrated supergravity device, pressure needs to be added during the circulation process, and the added pressure ranges from 0.01 MPa to 20 MPa.

9. The method of claim 4, wherein, The aging time is 24-96 h; the aging is carried out under pressure and supergravity in the aging and crystallization integrated supergravity device.

10. The method of claim 4, wherein, The crystallization conditions are that the crystallization temperature is 100-200 ℃, and the crystallization time is 1-96 h; and / or preferably, the pressurization in the pressurized crystallization is that the crystallization is again increased in pressure under the supergravity in the aging and crystallization integrated supergravity device; the increased pressure ranges from 0.01 MPa to 10 MPa, preferably from 0.1 MPa to 8 MPa.

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