A ZSM-5 molecular sieve and its preparation method

Abstract

This invention discloses a ZSM-5 molecular sieve and its preparation method. The molecular sieve is a prismatic interpenetrating body formed by the perpendicular intersection of two straight hexagonal prisms. This molecular sieve has novel morphological characteristics, being a prismatic interpenetrating body, and can be used in the field of catalytic production.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more particularly to a ZSM-5 molecular sieve and its preparation method. Background Technology

[0002] Molecular sieves, with their unique pore structure, tunable acidity, high thermal stability, and excellent shape selectivity, are important chemical catalytic materials. They are currently widely used in various fields such as petrochemicals, coal chemicals, and fine chemicals, including catalytic cracking, aromatic disproportionation, isomerization, selective oxidation, methanol-to-olefins, and methanol-to-aromatics processes. They also have potential applications in gas separation and purification, biomaterial synthesis, information communication, environmental energy, and novel assembled nanomaterials. High-efficiency molecular sieve catalysts have developed into an important new material.

[0003] CN115417424A discloses a method for preparing and applying a swollen silica-alumina molecular sieve precursor. The precursor is characterized by a framework of silicon, aluminum, and oxygen interconnected in a tetrahedral form, forming a novel two-dimensional swollen layered silica-aluminate material. It is obtained by hydrothermal synthesis using a bis-headed quaternary ammonium salt surfactant as an organic template agent.

[0004] CN113086990A discloses a method for preparing mesoporous molecular sieves, including the following steps: (1) Preparation of Y-type molecular sieve precursor: using silicon source, aluminum source and sodium hydroxide as raw materials, and deionized water as solvent to prepare Y-type molecular sieve precursor solution, and then aging to obtain molecular sieve precursor, wherein the molar ratio of each component is: (1~500)Na2O:Al2O3:(1~850)SiO2:(10~800)H2O; (2) Preparation of seed crystals: taking triblock copolymer P123 and sodium dodecyl sulfate SDS and dissolving them in deionized water, then adding Y-type molecular sieve precursor, stirring and assembling to obtain assembly product, then crystallizing, filtering, washing and drying to obtain high-regularity seed crystals; (3) Synthesis of mesoporous molecular sieves without template agent: adding seed crystals to Y-type molecular sieve precursor, stirring, then crystallizing, filtering, washing, drying and calcining to obtain high-regularity mesoporous molecular sieves.

[0005] CN111484035A discloses a method for preparing a ZSM-5 molecular sieve precursor and its application. The method includes mixing and stirring an organic amine template agent, water, a silicon source, and optionally an aluminum source, followed by a crystallization reaction. The molecular sieve is synthesized using conventional methods for mixing molecular sieve precursors, resulting in a single columnar molecular sieve. Summary of the Invention

[0006] This invention provides a novel ZSM-5 molecular sieve and its preparation method. This molecular sieve exhibits a novel morphological feature, being a prismatic perforated structure, and can be used in catalytic production.

[0007] The first aspect of the present invention provides a ZSM-5 molecular sieve, wherein the molecular sieve is a prism interpenetrating body formed by two perpendicularly intersecting straight hexagonal prisms.

[0008] Furthermore, in the prism interpenetrating body, each of the two right hexagonal prisms has two relatively large lateral faces and four relatively small lateral faces. The two relatively large lateral faces are parallel, and there are two relatively small lateral faces between each of the two relatively large lateral faces. In the prism interpenetrating body, the relatively large lateral faces of the two right hexagonal prisms are perpendicular to each other and penetrate each other, and the two adjacent relatively small lateral faces of the two right hexagonal prisms are in the same projection direction.

[0009] Furthermore, the right hexagonal prism has two bases, both of which are hexagonal.

[0010] Furthermore, the height h of the right hexagonal prism is 2-4 μm.

[0011] Furthermore, the distance 'a' between the two relatively larger lateral faces of the right hexagonal prism is 1-2 μm.

[0012] Furthermore, the length b of the base edge of the relatively large lateral face of the right hexagonal prism is 1.5-3 times that of a.

[0013] Furthermore, the prism interpenetrating body is a prism interpenetrating body in which two straight hexagonal prisms intersect in a cross shape.

[0014] Furthermore, the atomic molar ratio of silicon to aluminum (Si / Al) in the ZSM-5 molecular sieve is 20-∞.

[0015] A second aspect of this invention provides a method for preparing ZSM-5 molecular sieves, comprising the following steps:

[0016] A molecular sieve gel precursor is obtained by mixing silicon source, aluminum source, additives, template agent and water. Then, it is added to an integrated aging and crystallization hypergravity device along with the copolymer. The device is pressurized and rotated under hypergravity, and circulated. After the process is completed, aging is performed. Then, crystallization is carried out under secondary pressure to obtain the ZSM-5 molecular sieve.

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

[0018] Furthermore, in solution A, the molar ratio of silicon source, template agent, and water is SiO2:template agent:H2O = 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 silicon source is at least one of silica sol, tetraethyl orthosilicate, amorphous silicon oxide, and silicate, and the aluminum source is at least one of aluminum sulfate octadecylhydrate, aluminum isopropoxide, aluminate, and aluminate.

[0020] Further, the template agent is at least one selected from n-propylamine, n-butylamine, n-hexylamine, methylamine, ethylamine, ethylenediamine, butyrolactone, valproic acid, and caprolactone.

[0021] Furthermore, the additive is at least one of urea, diethanolamine, ammonium chloride, and ammonia water.

[0022] Furthermore, the molecular sieve gel precursor used needs to be passed into an integrated aging and crystallization supergravity device for circulation, with at least 3 cycles, preferably 3-8 cycles.

[0023] Furthermore, the cycle time is 5-120 min, preferably 10-60 min.

[0024] Furthermore, the supergravity rotation speed during the cycle is 500-5000 rpm, preferably 1000-3000 rpm.

[0025] Furthermore, after the molecular sieve gel precursor is introduced into the integrated aging and crystallization hypergravity device, pressure needs to be added during the circulation process.

[0026] Furthermore, the pressurization pressure is 0.01-10 MPa, preferably 0.05-8 MPa.

[0027] Furthermore, the copolymer includes at least one of random copolymers, alternating copolymers, block copolymers, and graft copolymers.

[0028] Further, the copolymer is preferably selected from at least one of P123, polystyrene-b-polymethyl methacrylate (PS-b-PMMA), and polybutadiene-styrene copolymer; wherein the molecular weight of polystyrene-b-polymethyl methacrylate (PS-b-PMMA) is 7500-50000; optionally, the polybutadiene-styrene copolymer is copolymerized from styrene and butadiene, and the molecular weight of the polybutadiene-styrene copolymer is 10000-50000.

[0029] Furthermore, the molar ratio of the copolymer to the silicon source, calculated as SiO2, is 0.05-10, preferably 0.2-10.

[0030] 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.

[0031] Furthermore, the pressure increase during the secondary pressurization is 0.01-10 MPa, preferably 0.1-8 MPa. The secondary pressurization increases the pressure based on the initial pressurization.

[0032] Furthermore, the crystallization conditions are a crystallization temperature of 100-200℃ and a crystallization time of 1-96 hours. The crystallization is carried out under secondary pressurization and hypergravity in an integrated aging and crystallization hypergravity device.

[0033] Furthermore, the hypergravity level in the integrated aging and crystallization hypergravity device is 10g-600g.

[0034] Furthermore, after crystallization, molecular sieves can be obtained by conventional washing and drying.

[0035] Furthermore, the molecular sieve obtained by the preparation method is a prism interpenetrating body formed by the perpendicular intersection of two straight hexagonal prisms.

[0036] Furthermore, in the interpenetrating body of the right hexagonal prisms, each of the two right hexagonal prisms has two relatively large sides and four relatively small sides. The two relatively large sides are parallel, and there are two relatively small sides between each of the two relatively large sides. In the interpenetrating body, the relatively large sides of the two right hexagonal prisms are perpendicular to each other and penetrate each other, and the two adjacent relatively small sides of the two right hexagonal prisms are in the same projection direction.

[0037] Furthermore, the right hexagonal prism has two bases, both of which are hexagonal.

[0038] Furthermore, the height h of the right hexagonal prism is 2-4 μm.

[0039] Furthermore, the distance 'a' between the two relatively larger lateral faces of the right hexagonal prism is 1-2 μm.

[0040] Furthermore, the length b of the base edge of the relatively large lateral face of the right hexagonal prism is 1.5-3 times that of a.

[0041] Furthermore, the prism interpenetrating body is a prism interpenetrating body in which two straight hexagonal prisms intersect in a cross shape.

[0042] Furthermore, the atomic molar ratio of silicon to aluminum (Si / Al) in the ZSM-5 molecular sieve is 20-∞.

[0043] 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.

[0044] The molecular sieve provided by this invention has a novel morphological feature, being a prismatic interpenetrating body, and can be used in the field of catalytic production. The method provided by this invention can significantly enhance grain shaping and forming effects, achieving mixed-enhanced growth at the microscale, and obtaining a novel molecular sieve with a special morphology. Attached Figure Description

[0045] Figure 1 These are SEM images of the molecular sieve obtained in Example 1;

[0046] Figure 2 The image shows the SEM image of the molecular sieve obtained in Comparative Example 1.

[0047] Figure 3 The image shows the XRD diffraction pattern of the molecular sieve obtained in Example 1. Detailed Implementation

[0048] The following embodiments will further illustrate the molecular sieve synthesis method provided by the present invention, but the scope of protection of the present invention is not limited to these embodiments.

[0049] In this invention, the scanning electron microscope (SEM) images of the samples were taken on a Hitachi S-4800II scanning electron microscope.

[0050] 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.

[0051]

Example 1

[0052] The silicon source was silica sol, the aluminum source was sodium aluminate, the template agent was n-propylamine, the additive was diethanolamine, and the copolymer was P123. Solution A was prepared by mixing SiO2:0.4 n-propylamine:500 H2O at a molar ratio of SiO2:0.2 diethanolamine:300 H2O. Solution B (Si / Al molar ratio of 50) was prepared by mixing Al2O3:0.2 diethanolamine:300 H2O. Solution B was slowly added to solution A. The resulting molecular sieve gel precursor was then passed into an integrated aging and crystallization hypergravity device. Copolymer P123 was added at a molar ratio of 0.2 P123:SiO2. The hypergravity level was adjusted to 100g, the hypergravity rotation speed to 2000 rpm, and the cycle was repeated three times for 20 minutes each time, with a pressure of 0.3 MPa. After aging for 72 hours, the pressure was increased to 0.4 MPa, and crystallization was carried out at 150℃ for 24 hours. After crystallization, the molecular sieve was obtained by washing and drying. The morphology is shown in [Figure showing morphology]. Figure 1 ,pass Figure 1 It can be seen that the morphology exhibits a prism-like interpenetrating structure. The height h of the right hexagonal prisms within the prism-like interpenetrating structure is 2–4 μm, the distance a between the two relatively larger lateral faces of the right hexagonal prism is 1–2 μm, and the length b of the base edge of the relatively larger lateral face of the right hexagonal prism is 1.5–3 times a. The XRD diffraction pattern of the molecular sieve is shown below. Figure 3 ,Depend on Figure 3 It can be identified as ZSM-5 molecular sieve.

[0053]

Example 2

[0054] The silicon source is silica sol, the aluminum source is aluminum isopropoxide, the template agent is n-butylamine, the additive is diethanolamine, and the copolymer is PS-b-PMMA (molecular weight 10000). Solution A is weighed with a molar ratio of SiO2:0.4 n-butylamine:500H2O. Solution B (Si / Al molar ratio 50) is prepared with a molar ratio of Al2O3:0.2 diethanolamine:300H2O. Solution B is slowly added to solution A. The resulting molecular sieve gel precursor is passed into an integrated aging and crystallization hypergravity device. Copolymer PS-b-PMMA is added with a molar ratio of 0.2 copolymer:SiO2. The hypergravity level is adjusted to 100g, the hypergravity rotation speed is 2000rpm, and the cycle is repeated 3 times for 20 minutes each time, with a pressure of 0.3MPa. After aging for 72 hours, the pressure is increased to 0.4MPa, and crystallization is carried out at 150℃ for 24 hours. After crystallization, the molecular sieve is obtained by washing and drying. The morphology of the molecular sieve is the same as... Figure 1 To present the morphology of the prism-shaped interpenetration, the height h of the right hexagonal prism in the prism-shaped interpenetration is 2-4 μm, the distance a between the two relatively larger sides of the right hexagonal prism is 1-2 μm, and the length b of the base edge of the relatively larger side of the right hexagonal prism is 1.5-3 times a. The XRD diffraction pattern of the molecular sieve is the same as... Figure 3 It is a ZSM-5 molecular sieve.

[0055]

Example 3

[0056] The silicon source is silica sol, the aluminum source is aluminum isopropoxide, the template agent is n-butylamine, the additive is ammonium chloride, and the copolymer is PS-b-PMMA (molecular weight 10000). Solution A is weighed with a molar ratio of SiO2:0.3 n-butylamine:200H2O. Solution B (Si / Al molar ratio 50) is prepared with a molar ratio of Al2O3:10 ammonium chloride:200H2O. Solution B is slowly added to solution A. The resulting molecular sieve gel precursor is passed into an integrated aging and crystallization hypergravity device. Copolymer PS-b-PMMA is added with a molar ratio of 0.2 copolymer:SiO2. The hypergravity level is adjusted to 250g, the hypergravity rotation speed is 2000rpm, and the cycle is repeated 3 times for 20 minutes each time, with a pressure of 0.2MPa. After aging for 72 hours, the pressure is increased to 0.4MPa, and crystallization is carried out at 180℃ for 48 hours. After crystallization, the molecular sieve is obtained by washing and drying. The morphology of the molecular sieve is the same as... Figure 1 To present the morphology of the prism-shaped interpenetration, the height h of the right hexagonal prism in the prism-shaped interpenetration is 2-4 μm, the distance a between the two relatively larger sides of the right hexagonal prism is 1-2 μm, and the length b of the base edge of the relatively larger side of the right hexagonal prism is 1.5-3 times a. The XRD diffraction pattern of the molecular sieve is the same as... Figure 3 It is a ZSM-5 molecular sieve.

[0057]

Example 4

[0058] The silicon source is silica sol, the aluminum source is aluminum isopropoxide, the template agent is n-propylamine, the additive is diethanolamine, and the copolymer is P123. Solution A is weighed at a molar ratio of SiO2:0.4 n-propylamine:500H2O. Solution B (Si / Al molar ratio of 50) is prepared at a molar ratio of Al2O3:0.2 diethanolamine:300H2O. Solution B is slowly added to solution A. The resulting molecular sieve gel precursor is passed into an integrated aging and crystallization hypergravity device. Copolymer P123 is added at a molar ratio of 10 P123:SiO2. The hypergravity level is adjusted to 150g, the hypergravity rotation speed is 2000rpm, and the cycle is repeated 3 times, each cycle lasting 20 minutes, with a pressure of 0.3MPa. After aging for 72 hours, the pressure is increased to 0.4MPa, and crystallization is carried out at 150℃ for 24 hours. After crystallization, the molecular sieve is obtained by washing and drying. The morphology of the molecular sieve is the same as... Figure 1 To present the morphology of the prism-shaped interpenetration, the height h of the right hexagonal prism in the prism-shaped interpenetration is 2-4 μm, the distance a between the two relatively larger sides of the right hexagonal prism is 1-2 μm, and the length b of the base edge of the relatively larger side of the right hexagonal prism is 1.5-3 times a. The XRD diffraction pattern of the molecular sieve is the same as... Figure 3 It is a ZSM-5 molecular sieve.

[0059]

Example 5

[0060] The silicon source used is TEOS, the aluminum source is aluminum isopropoxide, the template agent is n-propylamine, the additive is diethanolamine, and the copolymer is P123. Solution A was weighed with a molar ratio of SiO2:0.4 n-propylamine:500H2O. Solution B (Si / Al molar ratio of 50) was prepared with a molar ratio of Al2O3:0.2 diethanolamine:300H2O. Solution B was slowly added to solution A. The resulting molecular sieve gel precursor was passed into an integrated aging and crystallization hypergravity device. Copolymer P123 was added with a molar ratio of 0.2 P123:SiO2. The hypergravity level was adjusted to 250g, the hypergravity rotation speed to 2000rpm, and the cycle was repeated three times for 20 minutes each time, with a pressure of 0.3MPa. After aging for 72 hours, the pressure was increased to 0.4MPa, and crystallization was carried out at 150℃ for 24 hours. After crystallization, the molecular sieve was obtained by washing and drying. The morphology of the molecular sieve is the same as... Figure 1 To present the morphology of the prism-shaped interpenetration, the height h of the right hexagonal prism in the prism-shaped interpenetration is 2-4 μm, the distance a between the two relatively larger sides of the right hexagonal prism is 1-2 μm, and the length b of the base edge of the relatively larger side of the right hexagonal prism is 1.5-3 times a. The XRD diffraction pattern of the molecular sieve is the same as... Figure 3 It is a ZSM-5 molecular sieve.

[0061] Comparative Example 1

[0062] The silicon source is silica sol, the aluminum source is sodium aluminate, the template agent is n-propylamine, and the additive is diethanolamine. Solution A is weighed out at a molar ratio of SiO2:0.4 n-propylamine:500H2O. Solution B (Si / Al molar ratio of 50) is prepared at a molar ratio of Al2O3:0.2 diethanolamine:300H2O. Solution B is slowly added to solution A. The resulting molecular sieve gel precursor is passed into an integrated aging and crystallization hypergravity device. No copolymer is added, no pressure is applied, the hypergravity level is adjusted to 100g, the hypergravity rotation speed is 2000rpm, and the cycle is repeated 3 times, with each cycle lasting 20 minutes. After aging for 72 hours, crystallization is carried out at 150℃ for 24 hours. After crystallization, the spherical molecular sieve is obtained by washing and drying. See [link to relevant documentation]. Figure 2 Obviously, the morphology is different from that of the molecular sieve of the present invention. The XRD diffraction pattern of the molecular sieve is the same as that of the present invention. Figure 3 ,Depend on Figure 3 It can be identified as ZSM-5 molecular sieve.

[0063] Comparative Example 2

[0064] The silicon source is silica sol, the aluminum source is aluminum isopropoxide, the template agent is n-propylamine, and the additive is diethanolamine. Solution A is weighed out at a molar ratio of SiO2:0.4 n-propylamine:500H2O. Solution B is prepared at a molar ratio of Al2O3:0.2 diethanolamine:300H2O (Si / Al molar ratio is 50). Solution B is slowly added to solution A. The resulting molecular sieve gel precursor is passed into an integrated aging and crystallization hypergravity device. No copolymer is added. The pressure is 0.3 MPa, the hypergravity level is adjusted to 100 g, and the hypergravity rotation speed is 2000 rpm. The device is circulated 3 times, with each circulation lasting 20 minutes. After aging for 72 hours, the pressure is increased to 0.4 MPa, and crystallization is carried out at 150℃ for 24 hours. After crystallization, the spherical molecular sieve is obtained by washing and drying.

[0065] Comparative Example 3

[0066] The silicon source is silica sol, the aluminum source is aluminum isopropoxide, the template agent is n-propylamine, the additive is diethanolamine, and the copolymer is P123. Solution A is weighed with a molar ratio of SiO2:0.4 n-propylamine:500H2O. Solution B (Si / Al molar ratio of 50) is prepared with a molar ratio of Al2O3:0.2 diethanolamine:300H2O. Solution B is slowly added to solution A. The resulting molecular sieve gel precursor is passed into an integrated aging and crystallization hypergravity device. With a molar ratio of 0.2 P123:SiO2, copolymer P123 is added. No pressure is applied. The hypergravity level is adjusted to 100g, the hypergravity rotation speed is 2000rpm, and the cycle is repeated 3 times, with each cycle lasting 20 minutes. After aging for 72 hours, crystallization is performed at 150℃ for 24 hours. After crystallization, the spherical molecular sieve is obtained by washing and drying.

[0067] 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-5 molecular sieve, wherein the molecular sieve is a prism-shaped interlocking body formed by two perpendicularly intersecting straight hexagonal prisms; In the prism interpenetration body, each of the two right hexagonal prisms has two relatively large lateral faces and four relatively small lateral faces. The two relatively large lateral faces are parallel, and there are two relatively small lateral faces between each of the two relatively large lateral faces. In the prism interpenetration body, the relatively large lateral faces of the two right hexagonal prisms are perpendicular to each other and penetrate each other. The two adjacent relatively small lateral faces of the two right hexagonal prisms are in the same projection direction. The height h of the right hexagonal prism is 2-4µm; the distance a between the two relatively larger lateral faces of the right hexagonal prism is 1-2µm; the length b of the base edge of the relatively larger lateral face of the right hexagonal prism is 1.5-3 times a.

2. The molecular sieve according to claim 1, characterized in that, The right hexagonal prism has two bases, both of which are hexagonal.

3. The molecular sieve according to claim 1, characterized in that, The prism interpenetration body is a prism interpenetration body in which two right hexagonal prisms intersect in a cross shape.

4. The molecular sieve according to claim 1, characterized in that, The atomic molar ratio of silicon to aluminum (Si / Al) in the ZSM-5 molecular sieve is 20-∞.

5. A method for preparing ZSM-5 molecular sieve, comprising the following steps: A molecular sieve gel precursor is obtained by mixing silicon source, aluminum source, template agent, additive and water. Then, it is added to an integrated aging and crystallization hypergravity device along with the copolymer. The device is pressurized and rotated under hypergravity, and circulated. After the cycle is completed, aging is performed. Then, crystallization is performed under secondary pressurization to obtain the ZSM-5 molecular sieve. The molar ratio of the silicon source, template agent and water is SiO2:template agent:H2O = 1:0.1-0.6:5-1000; the molar ratio of the aluminum source, additive and silicon source is Si / Al = 0.5-∞, additive:Al = 0.01-50, H2O:Al = 5-500. The template agent is at least one of n-propylamine, n-butylamine, n-hexylamine, methylamine, ethylamine, ethylenediamine, butyrolactone, valproic acid, and caprolactone; the additive is at least one of urea, diethanolamine, ammonium chloride, and ammonia water. The copolymer is selected from at least one of P123, polystyrene-b-polymethyl methacrylate, and polybutadiene-styrene copolymer; the molar ratio of the copolymer to the silicon source, calculated as SiO2, is 0.05-10. The pressurization pressure is 0.01-10 MPa; the secondary pressurization pressure is 0.01-10 MPa; the aging time is 24-96 h; the crystallization conditions are a crystallization temperature of 100-200℃ and a crystallization time of 1-96 h.

6. The preparation method according to claim 5, characterized in that, The molecular sieve gel precursor is prepared by: preparing solution A with silicon source, template agent and water, preparing solution B with aluminum source, additive and water, and mixing solution A and solution B to obtain the molecular sieve gel precursor.

7. The preparation method according to claim 5, characterized in that, The silicon source is at least one of silica sol, tetraethyl orthosilicate, amorphous silicon oxide, and silicate, and the aluminum source is at least one of aluminum sulfate octadecylhydrate, aluminum isopropoxide, aluminate, and aluminate.

8. The preparation method according to claim 5, characterized in that, The molar ratio of the copolymer to the silicon source, calculated as SiO2, is 0.2-10.

9. The preparation method according to claim 5, characterized in that, The pressurization pressure is 0.05-8 MPa; and / or the secondary pressurization pressure is 0.1-8 MPa.

Images